The Molecular and Supramolecular Chemistry of Carbohydrates: Chemical Introduction to the Glycosciences

166 Pages·1998·9.41 MB·English

by  Serge David

._.__J::
The Molecular and Supramolecular

Chemistry of Carbohydrates:

Chemical Introduction to the Glycosciences
SERGE DAVID
Emeritus Professor, University ofParis-Sud, Orsay
Translated by

Rosemary Green Beau

Institute ofMolecular Chemistry, University ofParis-Sud, Orsay
OXFORD NEW YORK TOKYO
OXFORD UNIVERSITY PRESS
1997
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Journal (excerpts), July 14, 1837
Chimie Moleculaire et supramoleculaire des sucres!

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Translation and adaption ofthe First French language edition

© Oxford University Press, 1997

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tional books on organic chemistry. Handbooks and textbooks essentially
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describe contemporary methods for constructing covalent bonds with a few
or cover other than that in which it is published and without a similar

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the living world. Indeed there has been considerable progress in the synthetic
organic chemistry of carbohydrates during the past decades. The optimizing of
Published with the help ofthe Ministere de la Culture.
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new techniques and the introduction of new concepts have permitted most of the
~
A catalogue recordfor this book is available from the British Library
~ important reactions of organic chemistry to be extended to this family of com­
~ pounds. Much intense effort has greatly improved the outcome of the glycosida­
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(Data available) tion reaction, which was often inefficient using older methods. The author has

devoted half of this work to these synthetic aspects. However, with the current
ISBN 0198500475 (Hbk)

ISBN 0198500467 (Pbk)
evolution of research ideas, limiting a book on carbohydrates to the description
of the best methods for constructing carbon-carbon and carbon-oxygen covalent
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bonds boils down to dropping half the subject. One of the most important topics
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bonds. Some of this research has developed in a totally autonomous fashion with
respect to the living world. However, in the chemistry of oligosaccharides (see
Chapter 9) a great number of associations of this type are encountered, not only
with the macromolecular receptors present in living cells, but with inorganic
structures as well. Of course the complexity of natural organic receptors makes
the analysis of association types rather conjectural in the majority of cases, but
, :,e: b! 'M M';,w44S4; -~--=-.::;--=- _
Preface vii
vi Preface
jttcomhclT9uhheepua,sehi morAsvttla Teniise,eis f c ftehsmsir ,at a e dbeeeec uflprsl a er aiaes,anr odwer aipcoudibrnenlntiitt tloridg taa h,ion h tthl tnwohf nyem inyrcoer a pioedo ee lonrhhmlac xrlfd yoyueao fupr eistsp ttfesnaefhmsii eicdnmco atnosehc,d arr gr menhyelig'ht s nt he tiee o tcmhmgrmamotrehteh te etmss iei eo estncucmamxhdetnidhlnseaetmsei,a-s,dnm ,sa w.nd go tta nptiriieerhlfessnyoivtnie ma hec.sooewr l soet,scrffLi iiu,ai abcnl eteolglrhaalgl teydhfnrapn f b n tduaotuuwm·oeh nsttlsmaih e looaimdyr yncuiorli lnyodgelastirdhlvc ,nmr ey h aaeui sth pnaatb hsiacepdagl s evfo lhir ec a netntoHywrhiihi c dfcstebuo iteeiu tmeohcdrohrmlelo ensaiuidans socret- nt lahn dwutsiyidtgeh npt rohwnmeiM euonraotmilk nihv rsetsMC hiepepsttswodr h .ti by sr .cbahA tiyet aphotooien lclet orfcntethmeh uhku rt mqhosne l.tf a ueuthdaWa1itiigeeciiirt,ntoyeh r i2hmspts n ch,ft trrs ouahaooeoa nllnenlnu.bely.ydd­ydt­­. rtgbpcmwotcmheiieleaumemroaoon rscT crnbnaeelarduehy dootoei!lw.ie nvs)haas cb ,Dasateday beic cct nedniothihoccohrtnrgeeadhah asags cvegaayigtt on. eerertcnl mhiim y oTotdndftichahuidoseoieeoneens e s lcouss ydidg cynaifnu i. soono ludtfir toCt mrr fsiorskoc ta eo tfphnmaamnha nerapontrseoui t ewrf osrctotnoe oeahencellrit rreieia traesygngtydt tsieha aasovn geqtaoi lnsoissenayutvfa i , r zmesf aiwcfesotdmen ucph uclhd cohzeli oswa esolzacbbtdi tsw iroigiyy aen aidhrh opds elleeae atipdsesnaespxtvasse ht mzpic .ohesaes yiec arfptn Saimn hsgs sae ti s a rethtemrwnth arnisehtwoinethhp,e dah tgiceilttt esetcyiyh hhyscrrah etee.i n h(f t gaccmo ioTtgehmobehfr rlih rtedgeybsie iteetesmatnciax rndi.nojioicys onu dsisT ?ew mz naiy sodhpneTcoclsefieotgsitirshrn d vi sknaotaeoatssheean rn p,nia ded tvsbapnsura fealls oiederteorbgge aua r tgueoqcialrthtn tu.eaoousue w p ene Tuetr orhs uscpenlhop,eo deserc edi ieeo, fnnern wu sbfias itgactett venohhhhocthnlidenseeetl­ftt
raetmfleocstpsh tehree aamt tbhiea nmceee otifn tghse amnda jsoyrm cparobsoiuhmyds rsaptee ccihaleimziinsgtr iyn ltahbios rfaietoldr.i eWs ea nadr et hine wbeocualuds eh atvhee tmhee ainminpgre sosfi otnh eosef esntrteurcitnugr easn isa roidn layn dre dviesaolredde rsllyo wlalnyd, ,a bnudt tthhaist iiss
ptfaaHwdpthahrrrolesmooogea e wprmnutipn kooleteraeih s tewevlne we,csset di,eoabietr .thn,rdn urh yiTecisttn t ghetthidf ihn iaraitosoesougr cp dmft iiuaebr sslaeue m yaaa ncst nshesaioprcs n o atriosei tritnei a,zhf np tn t eoeeighetc trrrelrlsaee eixs htts s oop towttaab ieb umeon ohcvmtxgfotiohi ipc odkuvgosheui,lceer sr t si niibcmweulm-eouynasaaovet tiusk ianuenrf tengsrhiatnscis t toefo ch haahssrthre mt ,aohae tbrvbeppro iulxaiau omyniincttlcn. g to t pwe e a Tgipnourttoheisteptisuernened timllet fiacfd tcro,tge po o rurpoehte mmsx egaapt nrav iot ehcgram e reeaa lpc yaapplpblu ctsalasvemseioc ratlsastsyteeli.ie cuo nmcraaiTenute c o .mhscpnl cda.Weooce eer Oelssrt lles s et enhh feiifcwbobaeicestlrlsh riie e c leonog.bl on nsitoeTauccuh aedalohepelnddls
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HFgrioaeemenndruiasnodiosTmretau, ruia hl1nopebglre1gny wceh g. sh,at6 o rewtu t(,eoaflh Etaydet hSe mtne eto lehangaayarcepul l ktiai sfptisnCeaunho rg cggedNont ihcar)r wlRa i1 rieatfttsiS7mhaoett .h,etafar6 eud fnnf,tdaho l.hkdc s ertes toIc orwh nain Dienl hPnacl gao ettreateiteolchrumiprnnntfe.to ee agi hiqnTsrrnt.o ase ug Throl ee r,e'esr ssde e nbt Ahliicl ateoeeFiontincnlienldpotglsiigre n zn eoo cSiss i nfthLm eoi a iDocuefpnmntn bo,tid hzoiecas neytnrotnhe smos dMaeeo r iudi 1bvcrCe 7 v efdilplo.iinrai4gorirc uef autaithpdhncsoliaie da snRar t 1saenccie,7ot oedsiaA.nvnl 6enyl etau,aod ee rgbcaf trcSe oh n hiso,enredt aifcmdfC lt otPliaiio irroornmsemuontn cnryfa astyiecsco nt siti1twr elosit1 vrhonoia.ine2es­
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framework of this book is organic chemistry which seems to us justifiable since, Sen-itiroh Hakomori for his assistance in the elaboration of Chapter 16.
sooner or later, all interactions will be described at the molecular level. There
may be more practical applications. For example, according to one report Paris S.D.
(Raugel 1994), a top American biotechnology company was obliged to contact a Jan 1997
large industrial group capable of helping on an organic chemistry level.
For anything having to do with the relationship of carbohydrates to the living
world, we have put a great deal of importance on molecules with a very large References
distribution, often universal, with special attention to general mechanisms. This
is the viewpoint of biochemistry, which has led us to exclude enticing areas such Auzanneau, F. I., Mondange, M., Charon, D., and Szabo L. (1992), Carbohydr. Res., 228,
aboaresibfo s oactcvrmehierceit ntmaaioiloilngsn itl ornyhyltciae ogodrsoef isl sdseatuiedccgd c aau hirnsnas t ritatibohdni eeodn t epiuwcgrnesoli .ebt wscBl teio,ulm lft b n swag orlcetyro idcdnnioigcsdcce ousnrnonsosjmitun tweggh a aeemtn xeetascl ant eo(b pS aoptnhirroadiobnt dihasouei,n gcv,teh h se1eaor9 mv8cahe6nara)iny.mr ua Waaccllto seeom. r nwiTps tetlhiherciexes,

SRKhaeCi3unb7ganae-ree4lb,v, 5 o,P L.hV..y ,J.d .r NL.( .1i Rn9(1de9s9b4.8e,) ,r62 gL)4,, a3A ,BR d1.ev, 3c. 1hMC-e1aar3rctibh8boe.u
h,b y2ud6rr2 . ,R C2ah2he4mr-n2a. n3B,3 i.oM
ch.,e rann.,d 4 4M,2o7s7ih-u3z3z9a.m
an, M. (1993),
structure and problems of practical importance concerning microbial oligo­

saccharides. The two references cited are to articles among the most recent from
two European schools active in this field (Kenne et al. 1993; Auzanneau et al.

1992). We shall end these general comments with a practical warning: the draw­

ings are most often schematic and should not be used as a source of quantitative

data. For the latter, the reader should refer to the numerous tables in this work.
Contents

1. Configuration of monosaccharides 1

2. Conformation of monosaccharides and

their derivatives 17

3. Alkyl and aryl glycosides and glycosamines 42

4. Nomenclature 67

5. Reactions of hydroxyl groups 77

6. Reactions of carbonyl groups and hemiacetals 96

7. Changes of configuration, unsaturated and

branched-chain sugars 109

8. Sugars in chiral synthesis 128

9. Oligosaccharides: configuration and analysis 143

10. Chemical transformations and synthesis of

oligosaccharides 162

11. Associations with anions, cations, and inorganic

molecules 186

12. Sialic acids and sialylated oligosaccharides 208

13. Glycoconjugates 224

14. Structure of some crystallized sugar-protein

complexes 239

15. Antigens and antibodies. Lectins 250

16. ABH and related blood group antigens 265

17. Important recognition events involving

oligosaccharides in the living world 277

18. Oligosaccharides as ligands to DNA 296

Index 311
1 Configuration of monosaccharides

1.1 Glucose
Glucose is extremely soluble in water: 0.5 kg can be dissolved in 250 mL of hot
water. The addition of acetic acid to this solution brings about a slow precipita­
tion of crystals. This is one of various tautomers, referred to in the official
nomenclature as 'a-D-glucopyranose', a word whose exact meaning will be
defined later in this chapter. The absolute configuration of this solid is known
through the association of X-ray and neutron diffraction analyses which give the
23 bond lengths, the 42 valency angles, and the 69 torsion angles of this mole­
cule (Brown and Levy 1979). In the schematic representation 1.1 of this
configuration, carbons 2 and 3 of the chain are assumed to be in front of the
molecule and carbons 1 and 4 in the plane of the drawing. The other carbons and
the ring oxygen are at the back of the molecule.
6
4 CHzOH
HO~20
H
1
3
OH
1.1
One recognizes an oxane ring (tetrahydropyran) substituted by three
secondary alcohol functions in an equatorial orientation, a side chain carrying a
primary alcohol function and finally a hemiacetal hydroxyl carried by carbon 1.
This intramolecular hemiacetal is derived from the addition of the oxygen
carried by C-5 to an aldehyde function.
Starting from any glucose sample, an isomer of compound 1.1 can be pre­
pared by the following protocol: the sample is recrystallized in acetic acid, crys­
tals are then dissolved in ice water (100 mL for 100 g), filtered, ethanol (0.5 L)
is added to the filtrate to bring about a rapid precipitation. The obtained com­
pound has the configuration 1.2 in the solid state (Chu and Jeffrey 1968).
OH
1.2
2 The molecular andsupramolecular chemistry ofcarbohydrates
Configuration ofmonosaccharides 3
The only difference with molecule 1.1 is in the hemiacetal hydroxyl orienta­
HDO
tion. All substrates of molecule 1.2 are equatorial. There is a great underlying
simplicity in the D-glucose configuration in spite of its forbidding aspect for a
beginner. This observation may be a useful starting point for memorizing carbo­ a-anomer
f3-anomer
H-I equatorial
hydrate structures. Molecule 1.2 is called' j3-D-glucopyranose'. H-I axial
J4Hz
Isomers 1.1 and 1.2 are in tautomeric equilibrium in aqueous solution accord­ J8Hz
ing to equation (1.1).
(1.1) a-D-glucopyranose ,B-D-glucopyranose
Thus the optical rotation of an aqueous solution of the a-o-isomer, which
corresponds to [a]D20 + 112° immediately after dissolution, decreases to 52.7°
in a few hours. Conversely, the, optical rotation of the ,B-o-isomer increases
from 18.7°, the value at dissolution, to the same equilibrium value. This allows
the following calculation: [a]/[j3] = 38/62. The all-equatorial compound domi­
0.33H
0.67H
nates, but we will see in Section 2.6 that we must avoid seeing here the class­
ical rules of conformational analysis. These are the experiments which allowed
~~
ppm
the tautomeric equilibrium (1.1) to be observed for the first time, and for this I I I I I I

reason, it has kept the name of mutarotation. :'>.L. 5.1 5.0 4.9 4.8 4.7 4.6 4.5 4.4
The proton NMR spectrum in D20 gives similar results. The H-l proton Fig. 1.1 IH NMR signals of anomeric protons of a-and ,B-D-glucopyranoses.
carried by C-l shows a downfield signal, because of the two geminal oxygens,
pfO
separated from the group of other protons and easy to spot. Immediately after
dissolution, a 3J 4 Hz doublet is observed on the a-o-glucopyranose spectrum,
H-C-OH
due to an axial-equatorial coupling. Under the same conditions, a large 3J 8 Hz I pm
doublet on the ,B-D-glucopyranose spectrum is observed immediately after dis­ Ho-C-H
I
solution, because of a trans-diaxial coupling. At equilibrium both signals are
H-f-OH H-y-OH
observed (Fig. l.l).
CH
In fact, this aqueous solution contains other tautomers but in concentrations H-y-OH 0H
2
much too weak to show up during routine NMR studies. For the time being we CHzOH
1.4
will disregard their existence. It must be clear that tautomers 1.1 and 1.2 are two
chemically distinct molecules whose differences are not only revealed by their
1.3
physical characteristics, but also by their chemical and enzymic reactivity.
However, one observes that the C-l carbon is distinguished from others by its
unstable configuration, hence its particular name of an anomeric carbon.
1.2 Other carbohydrate configurations
Traditionally, glucose has been represented by the aldehyde parent 1.3 in which
only stable configurations are found. However, this tautomer is only present,
There are four other asymmetric carbons in the configuration 1.3, and thus 2 = 16
under any circumstance, in a very small concentration. 4
isomers, each having its own name. The reader will find a table of these sugars in
Aldehyde 1.3 is drawn using the Fischer projection fOnTIula. The hydroxyls
Chapter 4, which deals with nomenclature. The majority of these configurations
located below the average plane of the oxane are to the right, the hydroxyl situ­
are found in derivatized forms in living cells. To confine ourselves to the general
ated above is to the left. The correspondence for carbon 5 linked to the side
universally known constituents, we will cite D-mannose 1.5 and D-galactose 1.6,
chain is more difficult. The reader should remember that, using the Fischer pro­
epimers at C-2 and C-4 of D-glucose, respectively. We will encounter, just as fre­
jection, the vertical valencies recede from and the horizontal valencies project
quently, three sugars in which the hydroxyl at C2 has been replaced by an
towards the viewer. The viewer may then check that the heavy atoms of D­
acetamido group, called N-acetylglucosamine 1.7, N-acetylmannosamine 1.8 and
glyceraldehyde 1.4 can be superimposed on the portion corresponding to
N-acetylgalactosamine 1.9. Partially deoxygenated molecules are also observed,
carbons 4, 5, and 6 of oxanes 1.1 and 1.2.
such as L-fucose 1.10. All of these sugars with a latent aldehyde function are
Configuration ofmonosaccharides 5
The molecular and supramolecular chemistry ofcarbohydrates
4
FH

plO
FO FO
fO
H-~OH H-f-NHCOCH3
HO-f-H I H-f-H

Ho-C-H Ho-C-H

HO-C-H
HO-Ir- I
I H 0H It-9-0H
0H H-r­
H-r­ H-~-OH H-~-OH CH3CONH-f-H
H-~-OH
HzOH HzOH H()--C-H
HzOH I
0H
1.5 1.6 1.7 It-r-
It-yOH
CHzOH
FO FO
FO
H-~COCH3 HO-C-H
CHCONH-IC -H I 1.14
3
HO-C-H H-C-OH
HO-C-H
I I
H-f-OH
Ho-r-H H-?-OH With the exception of fucose, all these sugars have the same configuration on
0H
Ho-~-H the penultimate carbon as does the central carbon of D-glyceraldehyde. This can
H-~-OH
H-b: easily be explained because living cells produce all sugars from D-glyceralde­
HzOH HzOH H3 hyde, and the biosynthetic pathway does not involve, at any step, a cleavage
between the central carbon of D-glyceraldehyde and one of its four substituents.
1.8 1.9 1.10
Figure 1.2 shows the 'genealogical tree' of these monosaccharides. D-Fructose
results from the aldol condensation of dihydroxyacetone (nucleophilic partner) on
D-glyceraldehyde. This leads to either D-glucose or D-mannose by modifications
called aldoses. However, the latent carbonyl can also be a ketone, hence we
at C-l and C-2. D-Glucose is epimerized at C-4 to give D-galactose. The same
have ketoses such as the fructose 1.11. All sugars comprising a six-carbon non­
D-glucose loses C-l and undergoes some transformations at C-2 and C-3 to give
branched chain have been given the general name of hexoses.
D-ribose (there is another biosynthetic pathway, the pentose-heptose cycle, which
There are also five-carbon sugars, the pentoses, of which two representatives,
is more complicated but does not involve the penultimate carbon). Deoxyribose is
the D-ribose 1.12 and the deoxyribose (using the correct nomenclature, 2-deoxy­
produced by deoxygenation of D-ribose at C-2. The amination of D-fructose
D-erythro-pentose) 1.13, are infinitely more important than the others. A sugar
with nine carbons, the sialic acid 1.14, gathers on the same chain a carboxyl, a
ketone carbonyl, five alcohol hydroxyls and one amide function. The carbohy­
Sialic acid 2-DeoxY-D-ribose
drate chains are numbered by giving the lowest number to the carbonyl carbon.
All of these molecules belong to the group called monosaccharides.
r
r
N -Acetylmannosamine D-Glyceraldehyde D-Ribose
THzOH

CO CHO
rO 1 r
I I - -
Ho-C-H H-CI --OH H-CI--H N -Acetylglucosamine D-Fructose D-Glucose
I 0H
H-r-OH H-r-OH H-r-
0H H-(OH 1 1 1
H-b-OH
H-b:
HzOH HzOH zOH N -Acetylgalactosamine D-Mannose D-Galactose
1.12 1.13 Fig. 1.2 'Genealogy' of the major sugars of the D-series.
1.11
6 The molecular and supramolecular chemistry ofcarbohydrates Configuration ofmonosaccharides 7
followed by acetylation gives N-acetylglucosamine, epimerized to N-acetyl­ configuration determines the series is rather passive in the creation of the glyco­

galactosamine and N-acetylmannosamine. The aldol condensation of pyruvic acid sidic bond between monosaccharides.

with N-acetylmannosamine gives sialic acid.

Among the sugars 1.5 to 1.14, only fucose has the L-glyceraldehyde
configuration at its penultimate carbon. The biological precursor is D-mannose 1.3 Tautomerism
which is converted to a derivative of intermediate structure 1.15. The latter
undergoes epimerizations at C-3 and C-5, in agreement with the organic 1.3.1 General
cogtawhhotreeheee e smmLnr c-oiudgsatset lrtf'oyb srpxc eoioeyennir gyntasueltul dingroteaieauohtdretnys udt dchbs entaiuin atotc ct tnuroeha rn ettatfo hhlir egeesarsauun elprg aahsactluoraicsobrso bnpsahto htroi naasCl stt ee-f o6aussb. rn osoeTce rftar oiecvdo noaejnzmavd.yc o pImeaitldnte e itxtass ht n oippeyn he a perob hercsirnaopaopsurhrbysla t oontinenmtfhos yi.aetnl ett,Htiew eca or oncppwardratree htbuvthyaonew tndrtia,hoe yoanrin­stf, aEt0h1aty.-xut14daat7ceom .wk m 1Ti inb.eth3hiyrne. s t go.Bhs xteWutay htbfg eeowie lrfinehmot ayrh0av mat-oeiv5ouf en laao a l n roffooei fov af rtnde weae-yalmo d so leoetfoahnm touyh ktbtdeooeee mdtre we1 xeda.ocr3 ts lr fu ippahndyocageeriv nastiis hnntos geon f tsop aoteh to,sf esvi av s1epiep.rbr1-yromi i lcodaiethnriymfiid fr,ob aet1eflrh e r.cae2ena td ttprra brfercerioskonsun megblyn,ty lic1 nt oheo.g1 afx o 6tayf f rloga dosfneemi ndxa­
no way does this invalidate our deductions. six-membered one. At this point, we will complete our explanation of the terms
~3.H dogmatically introduced at the beginning of the chapter. Oxane ring sugars
° ° (tetrahydropyran) are pyranoses, while those with an oxolane ring (tetrahydrofu­
ran) are known as furanoses. The symbol a is defined with reference to the
H penultimate carbon. A simple explanation for this convention is based on the
carbonyl hydrate such as 1.18 corresponding to D-glucose. On paper, it is trans­
1.15 formed into furanose or pyranose by replacing one of the hydroxyls carried by
ioLffy-sLeienierggtihe uDst, s - twglhelheua ecvDroee-s s ebe Ciraoi-ne5cds h weihtmash sei1 sr5tte hr iyCes o-f5Lmo r-he garglssye cowthemiretae hDlt dra-ye gs.h ltyyWadcbeeele r a hcclaodovnenefhfi iygtgdauukerr aeactntoii oontnhnfi.e gi nuThtrahoabe ttii wotn nooa fmag ncredolsa u tshposes­f hiCtvhy-eedll yrabo.n yxSo ytmihxl ee-im sro sxeistmy rigcbcaetelnlrly eeo ddtfr saaaunn.g saTa lwrhcsuoi tashhr o e1rl e .d1fsue6pan elcatctn tiwdo t inot1 hct. h1aien7rr oiSaexredeyc tbgaiyeo- nnC a o4-n4.fd2 t o.h6Jr3e. C -pD-e5-nf.u uIrlfatnitmhoesa ert,ee m rceaasripnbeiocnntg­,
the sugars of the D-series are preceded by the prefix D such as D-glucose, We also have to consider the presence of a free aldehyde in solution and its
D-mannose, etc. The enantiomers of these hexoses belonging to the L-series are
hydrate 1.18 because it is known that hydrates of a-hydroxylated aldehydes are
called L-glucose, L-mannose, etc. Finally, whenever the configuration rather than relatively stable.

the molecule is to be designated, the words are written in italics as in D-manno, In fact, all of these tautomers exist in aqueous solution, but usually some are
D-gluco, D-galacto, L-manno, etc., derived from the current names of sugars. present in concentrations too low to be visible without sophisticated techniques.
This holds true for words appearing within a text or for a sugar named according For example, in the case ofD-glucose, tautomers other than a- and ,B-D-pyranoses
to the official nomenclature (see Chapter 4). These rules can be applied without are only present in insignificant amounts. The problem of the tautomeric content
difficulty to the pentoses. There are eight pentoses, pairs of enantiomers, divided of sugar solutions at equilibrium, generally aqueous, has stimulated a great deal
into two series, Dand L, depending on whether the penultimate carbon has the
D-glyceraldehyde or opposite configuration. The configuration of the pentose H
I
D-ribose is designated as D-ribo. CHzOH CHzOH HO-C-OH
The words 'D-series' and 'L-series' do not have the same biological meaning, I
doefp pernodteinings ,o n2 0w ihne tahlle,r bweelo anrge leoxockluinsgiv aetl ys utgo atrhs eo r'L a mseirnioes a ocifd asm Tihneo aamciindos' .a cTihdes Hi Hi H HoH--CCI --OHH
oligosaccharide sequences, parallel structures to polypeptides in tissues (but not I
directly coded), can be constructed from D-sugars as well as L-sugars, although H-r-0H
the first ones predominate in general. The following explanation may be sug­ OH OH Hy-OH
gested: the amino acids carbon whose configuration determines the series is mpH
linked to two functional groups, amino and carboxyl, involved directly in the

peptidic bond. On the other hand, the penultimate carbon of sugars, whose 1.16 1.17 1.18
8 The molecular and supramolecular chemistry ofcarbohydrates Configuration ofmonosaccharides 9
pocahrhfa eyitnmsivtieciesra telrm symte . (etLAhaeosntudg rusye sam bale1eccn9kat8nsu4o sr,wea t1lhte9hed9erg1 yte) h., c aChanolo lawn ttfteroeavrmr eyrpv ,tet iotrnhy gta r tabi sdtahoisteliiacyot niaot,er newc, h nhwnoiicetqh wtu hgeieisl vl m efoisorf s sptct r adeprciobsewcoduheesynrsfdc usreela pttione­ oItphnrfe e t ashrsleeluf rroeealpscue tevirvnaaetrt,iy oiisnnnudgagel ax frr,cos oo mnarr dte1hi t etdio oeu nt3lest0rr, amavstioimno elomedstu p bachybhe s rmoesrsoep, attaishonuandrt. i tnThtgheh e tip hsrc eroo ecclquehudmaiunrnrege sei st aa ibnkss euocsrlo ruaontrudeo nuusdcntatedabd ni Ilc ibtheyy.,
ttrhheeea cpteiroqensuesiln, itba cnriodun mtthe.ex tfS.a oOsltevf sectno ptusor ssiesni bi slwoel haditecirohinv amotfiuz ata attriaoounttao rtmeioaencr t imiosn usss tlw oniwollt, bnleoo tuwics eedate.b mlyp meroadtuifrye p(s6ua lrAjft.iotmmcnuo)al ntafeirgldll yi on degtihxv epain re6 yn sxsltbia ve1tein5o z0rnee agmnrUeym l pa pctooholraylsuss. emtysn re ahndaeas p bbteeedae dnfs od roe sftc hsretirbsieec dtls.y eT pchaoirsna ttciroaotnlilsoe,nd tehdxeica hmuasenet geoersrf
is used in the Ca2+ form with a flow rate of 0.5 mL min-I. In these experiments
1.3.2 Gas chromatography (Honda et al. 1984), the authors determined sugars in an eluent by transforma­
Shyudgraorgs eanr eb oenxdtsr,e msineclye istt iasb piloizsseidb lien f osro eliadc ha nhdy dlrioqxuyidl tpo hbaes eas d obny oar onre atwn oacrkce op­f tsiaorny itnotdoa ay duesriinvgat imveo daebrsno rebqinugip amt e2n8t0. nFmig,u breu t 1t.h3i ss whoowulsd tcheer tdaaintaly o nbotat ibnee dn ewceitsh­
tStohura.bt sTtwhitehu ettinoo tnat lho edf e amsltlro ualeccctiiduoilnce ohbfye dtghriionsg sne entotsw bdoyer kcSo iims( CnpHoots3 hep.o ssSusupibgplareer ssa ste ctsae nmannpoyet r paboteus sreidbsiis lbtiietlylleo dow.f tDh-iTgs lhuceca onas -eb,a enD dc- galar3rl-aifecudtro asoneuo, tsa enbsde e tDwqu-emielinabn r-na2ote5s e t oa(noHd oq nu-d4ica5k °elCyt a tlou. sb1ine9 g8s 4es)pp. aercaitaeld saot l0v-e4n°tsC ,w bituht
hydrogen bonding. The accumulation of methyl groups on the outside-IS in D-galactose and D-fucose.
the case of glucose-gives the molecule the approximate form of a sphere
limited by 45 neutral hydrogen atoms with minimal cohesion. Although ren­
dered considerably heavier, the molecule becomes volatile. Thus the derivative
of a-D-glucopyranose in which every OH is replaced by OSi(CH3h boils at D-glucose
107°-110°C under 0.1 mm ofHg. Thus the persilylated sugar derivatives can be
rapidly separated by gas chromatography. In a classical silylation procedure, D-rnannose

sugar (10 mg) is dissolved in pyridine (1 mL), then hexamethyldisilazane
{3-p

(Me3SiNHSiMe3, 0.1 mL) and cholorotrimethylsilane (0.1 mL) are added. Each
hydroxyl is silylated according to equation (1.2). The reaction is normally
D-galactose

completed in 5 min at room temperature.

(1.2) 3ROH + CISiMe3 + Me3SiNHSiMe3 --7 3ROSiMe3 + NH4CI 50 40 30 20 10 0
Minutes

In order to follow the mutarotation, the sample (5 j.tL) is quickly dissolved in

Nla,tNin-gd immiextthuyrelf oisr madadmedid, ea lalnodw ethde toso wluatrimon t ios rcoooomle tde minp leiqrautiudr en,i ttrhoegne nap. pTlhieed s tioly a­ Fabigso. r1p.t3io nS aet p2a8r0a tniornn. oFfo arn ootrhneerr sc obnyd HitiPoLnsC saete 4 t°eCxt,. eAludeanptt,e wd afrtoemr-a Hceotnodnait reitl ea l.( 2(01:98804, )v. !v); ordinate,
column. Used at ISO-200°C, the column contains a liquid with a high boiling
point, adsorbed on a powdery solid phase. Utilizing this method, it is possible to 1.3.4 Circular dichroism
observe as many peaks on the chromatogram as there are tautomers in noticeable
qa umaneatistuiersa binle s qouluatniotinty. .I dentifying the peaks requires the isolation offractions in cCairrbcounlayrl dtaicuhtoromisemrs mwehaicshu raerme epnatrst ihcauvlaer lbye eqnu iccoknlys ifdaedriendg .i nC oarrdbeorn tyol ocobmseprvoeu nthdes
absorb near 280 nm due to the n7T* transition of the C=O double bond. The
beginningofthisbandisvisibleinaqueous solutionsofsugars, butbecauseofits
1.3.3 High-pressure liquid chromatography (HPLC) weak intensity, it is largely masked by the shoulder of a more intense one. For
tDiwinoiicrtnrhee ciavsts acianrhy grtio en(cmHgh aindctiikoqmsgu re1ean9 psw8hi8ohi)cno. ssaT enfh raueol symaesd iss3ino o trotbfh afe1rn e5tce ih,#s Le oimmnr initsnhete ra1y rf0l oy ort mfof r oe 1oel5if,g mscoumsogan caaocrndsha iaislnrypi tedaircqesasue led iocs p ouarlsaru tpsmioicdnlleulsys­. aftthhe rreiese spnrurceeleats s eooonnffc ,et ehLe eox- tfpi ernaRe cc st=ieiro nc!nicu.e elca aborne fdnt awiocnteh aebrsnoey ilsdmemifrmte -icenatt lnrtyhidc i d srce irgateerhgrbtmi-oocnininr ,aec tdduhj.la aaBtct oeiusrnt y ttw o pt ohos aaltathy rieais z nccea hdera xblritoaginnchyctte.tl ir.To iTsnhta iidcsb i lfiies­s
Preparative columns (2.5 x 30 cm) are also used. Elution is only possible under 1.1 gives a selection ofresults.
Configuration ofmonosaccharides 11
The molecular and supramolecular chemistry ofcarbohydrates
10
is routinely used in most laboratories, reveals only the and {3-pyranose signals
Table 1.1 Circular dichroism of sugars in aqueous solution at 20 D C (from (¥-
in solutions of n-glucose and n-mannose, while in solutions of n-galactose, two
Hayward and Angyal 1977) (reproduced with kind permission from Elsevier
other very weak peaks show the presence of two furanoses. The carbonyl signal
Science). is visible in the l3C NMR spectrum in a 4M solution of fructose (Angyal1984).
Sugar 103 !::l.e A (nm) a -Carbon configuration Further, 13C NMR is used with sugars labelled at C-l by a synthetic method
which multiplies the signal intensity by 100. Using special accumulation and
-0.469 285 R
o-ribose prolonged procedures, the six tautomers of n-glucose at 37DC can be observed
-0.170 287 R
o-galactose -0.0222 285 R (Fig. 1.4). Because of the disproportion of concentrations a quantitative present­
o-glucose
+0.0535 292 S ation is not possible and the reader should consult Table 1.2.
o-mannose
The utilization of sugars labelled at C-l has another equally important advan­
5,6-di-O-methy1­
o-glucose (1.19) -9.57 289 R tage in that we can observe the coupling of C-l with the l3C nuclei present in
o-fructose +6.72 273 S very small amounts at other positions of the sugar, which in general only show
1-deoxy-o-fructose (1.20) +138 274 S IJ couplings. Thus we have a tool to facilitate the interpretation of the spectrum
(Barker and Serianni 1986; King-Morris and Serianni 1987). A supplementary
Table 1.1 first shows that As is positive when the configuration of the adja­ simplification is carried out using the INADEQUATE technique which only
cent chiral center is S, and negative when this configuration is R. This is a records the signals due to carbons coupled at C-l. The parameters can be
general rule, verified by 33 examples. Next one notes the considerable differ­
ence in the order of magnitude between the non-substituted aldehyde sugars and 4 5
the ketone sugars, suggesting that the concentration of the carbonyl tautomer is
much higher in the latter. A higher value is also noted with 5,6-diO-methyl-n­
glucose 1.19. This derivative cannot exist in the form of a pyranose and it essen­
tially has the furanose form in solution, but the considerable increase of Ae I 2 3
....
indicates that the difference of free enthalpy between aldehyde and furanose is 1
I . .
less than between aldehyde and pyranose. At the moment the deoxy sugar 1.20
holds the absolute record for these values. Probably the greater natural stability I I I I I
of the ketone function is reinforced by suppressing the inductive effect of the 206 104 102 100 98 96 94 92 90
alcohol function. These values cannot be used to determine carbonyl tautomers Fig.l.4 13C NMR spectrum of [P3C]-o-glucose in water at 37°C. Abscissae: displacements in ppm
exactly because we do not have access to the As values of pure compounds. from Me4Si. Ordinate: qualitative intensities. Signal attributions: (1) aldehyde; (2) (3-o-glucofuranose;
Taking the unit as an approximately plausible value, we obtain concentrations of (3) a-o-glucofuranose; (4) (3-o-glucopyranose; (5) a-o-glucopyranose; (6) gem-diol (from Maple and
Allerhand 1987) (reproduced with kind permission from the American Chemical Society).
the same order by this calculation as by other methods.
yHO ~3
Table 1.2 Tautomeric composition of sugars in D 0 according to Angyal
2

It-C-OH fO (1984; 1991) (reproduced with kind permission from Academic Press).
I
HO-C-H Ho-C-H Sugar I Pyranose Furanose Aldehyde Aldehydrol
I I (0C) a f3 a f3
H---y-OH H---rOH
H---y-0H o-Glucose 27 38.8 60.9 0.14 0.15 0.0024* 0.0045
H---f-OCH3 D-Mannose 21 68.0 32.0
mpH
CHOCH D-Galactose 31 30 64 2.5 3.5 0.02
2 3
D-Ribose 31 21.5 58.5 6.5 13.5 0.05
1.20 2-Deoxy-D-erythro-pentose 30 40 35 13 12
1.19
Fructose 31 2.5 65 6.5 25 0.8
Fructofuranose­
1.3.5 Nuclear magnetic resonance 1,6-diphosphate (1.21) 6 13 86 0.9
Everything that has been said about glucose can be applied to other aldoses. The I-Deoxy-fructose (1.20) 37 4 75 6 9 6**
H-1 proton signals of different tautomers in solution in deuterium oxide appear
*at 37°C; **ketonic tautomer.
_ •• • __,-- 0_..1 ...~.... th.. nth...." The oroton NMR technique. as it