the biochemistry of the amino acids

623 Pages·2012·18.46 MB·English

THE BIOCHEMISTRY OF
•
THE AMINO ACIDS
BY
H. H. MITCHELL
PROFESEIOR OF ANIMAL NUTRITION, COLLEGE OF AGRICULTURE,
UNIVERSITY OF ILLINOIS
AND
T. s. HAI\1ILTON
ASSOCIATE IN ANIMAL NUTRITION, COLLECE OF ACRICULTURE,
UNIVERSITY OF ILLINOIS
American Chemical Society
l\lonograph Series
BOOK DEPARTMENT
The CHEMICAL CATALOG COMPANY, Inc.
419 FOURTH AVENUE, AT 29TH :;rREET, 1\jEW YORK, U. S. A.
1929

GENERAL INTRODUCTION
American Chemical Society Series of
Scientific and Technologic Monographs
By arrangement with the Interallied Conference of Pure and
Applied Chemistry, which met in London and Brussels in July,
1919, the American Chemical Society was to undertake the pro
duction and publication of Scientific and Technologic Mono
graphs on .chemical subjects. At the same time it was agreed
that the National Research Council, in cooperation with the
American Chemical Society and the American Physical Society,
should undertake the production and publication of Critical
Tables of Chemical and Physical Constants. The American
Chemical Society and the National Research Council mutually
agreed to care for these two fields of chemical development,
The American Chemical Society named as Trustees, to makE
the necessary arrangements for the publication of the mono
graphs, Charles L. Parsons, Secretary of the American Chemical
Society, \Vashington, D. C. f John E. Teeple, Treasurer 01 thE
American Chemical Society , New York City; and Professor
Gellert Alleman of Swarthmore College. The Trustees have
arranged for the publication of the American Chemical Society
series of (a) Scientific and. Lp) Technologic Monographs by the
Chemical Catalog Compan?W~w York City. .-
The Council, acting through the Committee on National Policy
of the American Chemical Society, appointed the editors, named
at the close of this introduction, to have charge of securing
authors, and of considering critically the manuscripts prepared
The editors of each series will endeavor to select topics WhICh
are of current interest and authors who are recognized as author
ities in their respective fields. The list of monographs thus far
sccured appears in the publisher's own announcement elsewhext
in this volume.
3
4 GENERAL INTRODUCTION
The development of knmvledge in all branches of science, and
especially in chemistry, has bee-n so rapid during the last fifty
years and the fields covered by this development have been so
varied that it is difficult for any individual to keep in touch with
the progress in branches of science "Outside his 0llYn specialty_
In spite of the facilities for the examination of the literature
given by Chemical Abstracts and such compendia as Beilstein's
Handbuch der Organischen Chemie, Richter's Lexikon, Ostwald's
Lehrbuch der Allgcmeinen Chemic, Abegg's and Gmelin-Kraut's
Handbuch der Anorganischen Chemie and the English and
French Dictionaries of Chemistry, it often takes a great deal
of time to coordinate the knowledge available upoh a single topic.
Consequently when men who have spcnt years in the study' of
important ·subjects are willing to coordinate their knowledge
and prcsent it in concise, readable form, thcy perform a service
of the highest value to their fellow chemists.
It was with .a clear recognition of the usefulness of reviews of
this character that a Comm-ittee of the American Chemical
Society recommended the publication of the two series of mono
graphs under the auspices of the Society.
Two rather distinct purposes are to be served by these mono
graphs. The first purpose, whose fulfilment will prohably render
to chemists in general the most important service, is to present
the knowledge availnble upon the chosen topic in a readable
form, intelligible to those whose activities may be along a wholly
different line. :Many chemists fail to realize how closely their
investigations may be connected with other w~rk which on the
surface appears far afield from their own. These monographs
will enable su.ch men' to form closer contact with the work of
chemists in other lines of research. The second purpose is to
promote research in the branch of science covered by the mono
graph, by furnishing a well digested survey of the progress
already made in that field and by pointing out directions in
which inveBtigation needs to be extended. To facilitate the
attainment of this purpose, it is intended to include extended
references to the literature, which will enable anyone interested
to follow up the subject in more detaiL If the literature is so
voluminous that a complete bibliography is impracticable, a
critical selection will be made of those papers which are most
important.
GENERAL INTRODUCTION 5
The publication-tlf these books marks a distinct departure in
the policy ·of the American Chemical Society inasmuch as it is
a serious attempt to found an American chemical literature ·with
out primary regard to commercial co~sid('rations. The su('cess
of the venture will depend in large part upon the measure of
cooperation whie!,! can be secured in the preparation of books
qealing adequately with topics of general interest; it is earnestly
hoped, therefore, that every member of the various organizations
in the chemical and allied industries will recognize the impor
tance of the enterprise and take sufficient interest to justify it.
AMERICAN CHEMICAL SOCIETY
BOARD OF EDITORS
Sci£!.Ilti-Sc Serics:- Technologic Series:
\VILLIAM A. NOYES, Editor, HARRISON E. HOWE, Editor,
GILBERT N. LEWIS, ~'ALTER A. SCHMIDT,
LAFAYETTE B. MENDEL, F. A. LIDBURY,
ARTHUR A. NOYES, ARTHUR D. LITTLE,
JULIUS STIEGLITZ. FRED C. ZEISBERG,
JOHN JOHNSTON,
R. E. \VILSON,
E. R. WEIDLEIN,
C. E. K. l\IEES,
F. W. WILLARD.

PREFACE
The purpose of a review of any field of knowledge is only partly
served by a description of the work that has been done in that field.
If no attempt is made to reconcile' the results of experimental study,
the review is little more than a chronologically arranged series of ab
stracts. Any effective attempt to reconcile experimental results requires
a critical consideration of them and of the methods by which they have
been obtained. Wherever two investigations along similar lines have
been interpreted in a contradictory fashion, the reviewer must deter
mine if possible whether the contradiction is only apparent, because of
what appears to be a misinterpretation of one or the other series of
data, or whether one or the other investigation is rendered totally or
partially invalid by the use of faulty or inadequate methods of study.
Of course, it may not be possibJe to effect a conciliation on ,eith~r basis,
so that the unraveling of the difficulty must wait upon further experi
mental inquiry. In fulfilling the most useful function of a monographic
review the judgment of the reviewer· must thus be exer6sed in apprais
ing each investigation cited, in assessing its value and its significance.
The field of animal gr~zP,ewistry and of nutritional physiology has
been experiencing a rapid expansion during the last two decades, and
inevitably with so many laboratories and so many investigators attack
ing the many new problems opened up by each extension of the horizon,
a variety of investigational methods and working hypotheses are being
used. If some are of limited usefulness, and if others become antiquated
in the light of the newer accretions of knowledge, they should be dis
carded, but so frequently they are not. Those who attempt to make
an accounting of the true progress of the science from time'to time miss
an opportunity and evade a responsibility if they do not, to the best of
their ability, attempt a discrimination between facts and what possess
only the appearance of facts, between warranted theories and outworn
heirlooms, and between methods of study that at best can establish
only a certain probability in favor of an outcome, and properly con
trolled experimentation. In its contemporary rapid expansion in volume
of research, the science of nutrition is in greatest danger from the
Q
10 PREFACE
complacency of its devotees, arising, quite naturally, from the apparent
ease with which new truths may be uncovered. However, an accounting
of progress actually made and an avoidance of a \rast amount of mis-,
directed experimentation requires quite a different attitude of mind.
Criticism, if it does nothing more than shatter this complacency and
arouse discussion of fundamentals, will justify itself, though in itself
it may be opinionated and ~arped by purely personal 'viewpoints.
The review of any field of scientific research affords ample illus
tration of the human quirks in the interpretation of experimental data
so well and so sympathetically described by D. Noel Paton in an address
before the British Association for the Advancement of Science in 1919:
"It is so difficult to avoid for_cing the interpretation which appeals
to us. But it should be recognized that the evidence, when set down
quite simply and without comment, should lead others to the same con
clusion as that to which we have arrived. We are not justified in dressing
it up in order to secure it more ready acceptance. In doing so, we cease
to be scientific men and become special pleaders.
"Yet this dressing up of one's view so as to make it convincing is
one of the most tempting of crimes-a crime which all of us, usually
nnconsciously, have doubtless committed in our time and will go on
committing. And the worst of it is that the abler the exponent, the
greater is the harm done. Every part of physiology affords startling
examples of this .... It is so difficult to say, 'the evidence is incon
clusive, to give the verdict of "Not proven." ' ... An attractive in
terpretation, boldly stated by an able advocate, is apt to seize the
imagination even of a critical physiologist and to lead to an abrogation,
of judgment and a blind acceptance. Especially is this the case when
the work is not in our own special line and when it is announced by a
due flourish of trumpets and is's upported by the invention of more or
less incomprehensible Greek words devised by some classical colleague.
Dangerous and unscientific as is this championing of one interpretation
of a series of observations or experiments, it has not infrequently helped
forward the advance of knowledge. It has often stimulated other
workers and led to the true solution of the problem. ..."
The review contained in the following pages of the present status
of the subject of the biochernistry of the amino acids and their role in
animal metabolism has been written in accordance with these ideas of
the function of such a contribution. The authors are well aware of the
dangers of passing jUdgment upon research covering such a wide field,
PREFACE 11
with only a small part of which first hand acquaintance has been
gathered in the laboratory. Doubtless errors in judgment have been
made, but much of the discussion offered rnay be of value by reason
of the fact that it has been written by comparative outsiders, unham
pered by the precedents and traditions unconsciously guiding investiga
tion and directing interpretation in each sub-field of study. We have
not been influenced by the prejudice so often expressed against "de
structive criticism," believing that the pointing out of error is a service
in itself, though possibly of a lower ordeI' than the correction of an
error. Unfortun~ely, not all situations permit of this higher criticism,
by reason of the incompleteness of available information, if not of thc
shortcomings of the reviewer.
The sections concerned with the chemistry of the amino acids deal
with principles rather than with technical details and are not in any
sense of ~he word a laporatory guide. :l\'[uch material that it was in
tended to include i11 these sections has been curtailed or omitted entirely
because of the unexpectedly large dimensions the book was assuming.
The physiology of the amino acids has been considered Lroadly, not
forgetting its bearing on the practical problems of anit:J:).al nutrition.
Attention has been almost entirely confined to the recent developments
and to the present status of each subject discussed. A historical treat
ment of the subject is undoubtedly of great value, and its practical
elimination frorn this book is not to be construed as a denial of this
value, but, after all, the purposes to Le served by a study of the de
velopmcnt of scientific thought and method are different from the
purposes of this book, i.e., an appraisal of the extent of knowledge in
the fields considered as well as of its limitations. It is well to know the
facts of a science, since their acquirement is the goal of scientific
investigation, but it is also well to consider what is not known, since
in these directions future progress is to be made.
The authors take great pleasure in acknowledgi~g the assistance of
Miss M. Helen Keith in the preparation of this monograph. With her
aid it has been possible t9 consult a large majority of all references
cited, in order·to insure an accurate description of the results obtained
and a fairer judgment of their value and significance. Her acquaintance
with the current literature and her daily contact with it in the course
of her duties as a member of the staff of the agricultural experiment
station, have contributed largely to the completeness of each chapter
of this book, and of the bibliography appended to each. It is believed
12 PREFACE
that the usefulness of the monograph .to those cO,!1cerned directly with
the topics discussed has been enhanced by definite reference to the
literature for each fact or figure cited.
H. H. MITCHELL,
T. S. HAMILTON.
Urbana, Ill.