Drug Receptor Interactions in Antimicrobial Chemotherapy: Symposium, Vienna, September 4–6, 1974

308 Pages·1975·9.55 MB·English

by  Fred E. Hahn (auth.)

Topics in Infectious Diseases
Vol.l
Drug Receptor Interactions
in Antimicrobial Chemotherapy
Symposium, Vienna, September 4-6, 1974
Edited by
J. Drews and F. E. Hahn
Springer-Verlag
Wien New York
Drug Receptor Interactions
in Antimicrobial Chemotherapy
Sandoz-Symposium, Vienna, September 4-6,1974
With 130 figures
Prof. Dr. Jiirgen Drews
Sandoz Forschungsinstitut Gesellschaft m. b. H.
Vienna, Austria
Prof. Fred E. Hahn, Ph. D.
Walter Reed Army Medical Center
Washington, D.C., U.S.A.
This work is subject to copyright.
All rights are reserved, whether the whole or part of the material is concerned,
specifically those of translation, reprinting, re-use of illustrations, broadcasting,
reproduction by photocopying machine or similar means, and storage in data banks.
© 1975 by Springer-Verlag/Wien
]SHN-13:978-3-7091-8407 -3 c-]SHN -13:978-3-7091-8405-9
DO]: 10.1007/978-3-7091-8405-9
Introduction
The concept of chemotherapy as originated by Paul Ehrlich is based
on the premise that antiparasitic drugs must have two properties:
they must first bind to specific structures of the parasite which
Ehrlich called chemoreceptors. Subsequent to their attachment to the
chemoreceptor and by virtue of this binding they must possess the
capacity to kill the parasite. Since the host which is to be cured
of an invading parasite also contains a large number of chemoreceptors,
that have the potential to bind toxic compounds, the task of the chemo
therapist is to identify chemoreceptors of the parasite which are .not
represented in the host and to design drugs which bind selectively to
them~ In this context, Ehrlich called· for "the complete and exhaustive
knowledge of all the different chemoreceptors of a certain parasite"
as a "sine qua non for success in chemotherapy".
Paradoxically and in spite of the fact that chemotherapy has become a
very advanced and successful therapeutic discipline, few of its tri
umphs have been achieved by following Ehrlich's original precepts. On
the contrary, in the overwhelming majority of cases, effective drugs
have been discovered without any knowledge of their chemoreceptors,
and these drugs themselves have conversely been used as tools to study
the nature of the chemoreceptors involved. In other words: chemother
apy, notably antibacterial chemotherapy, has been successful without
ever living up to the fundamental standards put forward by Paul Ehr
lich.
Two reasons should lead us to reassess the basic postulates of chemo
therapy: the first one can be deduced from the present state of anti
microbial chemotherapy itself. Clearly, the rate of progress in this
area as judged by the number of genuinely novel drugs becoming avail
able to the physician each year has slowed down. The rediscovery
problem in the search for new antibiotics and the paucity of known
biochemical differences between parasites and hosts which might be
exploited for the design of antimetabolites are contributory factors
to the decreasing rate of discovery of new chemotherapeutic drugs.
Moreover, the current situation is characterized by the appearance
of new problems such as multiple drug resistance of bacteria and the
increasing frequency of infections with gram-negative pathogens and
fungi as well as by the persistence of old problems best exemplified
by our distressing inability to make progress in the area of antiviral
chemotherapy.
The second, and more positive reason is that since the days of Paul
Ehrlich t~emendous advances have been made in the fields of physical
chemistry, biochemistry, biophysics, genetics and molecular biology.
Studies on the molecular structure of drug-receptors and on the inter
action of such receptors with antimicrobial compounds should, there
fore, have a distinctly better chance of success today than they had
VI
sixty years ago when their necessity was first recognized. While du
ring the first decades following Ehrlich's death (1915) chemotherapy
research was constrained to use empirical search and development pro
cedures, we feel that with the current state of the art the field can
no longer afford the luxury of unguided empiricism; the time has ar
rived to apply the knowledge of principles and mechanisms of drug
action which has been gained during three decades of intensive re
search to premediated efforts to develop novel chemotherapeutic agents.
It is for these reasons that the Sandoz Research Institute decided to
ask a number of scientists well known for their work in areas such as
structure-activity relationships, structure and function of plasmid
DNA, bacterial protein biosynthesis and bacterial enzymes to reassess
their own work in the context of its possible applicability to the
search for new antimicrobial drugs or to the improvement of already
existing compounds. In selecting the general topics for our symposium
on drug-receptor interactions in antimicrobial chemotherapy we were
led by the intention to include only such areas of research which had
already contributed to the generation of novel chemotherapeutic agents
or in which relevant practical contributions towards this goal could
be expected in the forseeable future. We believe that the general sub
jects, microbial enzymes as drug-receptors, ribosomes as drug-receptors,
DNA as drug-receptors and, last but not least, a general consideration
of the receptor hypothesis, satisfy these criteria.
The proceedings of this symposium are not meant to compete with more
systematic texts on molecular aspects of chemotherapy or pharmacology.
The exciting responses of basic scientists to the challenges and prob
lems of drug therapy and drug development were revealed during this
symposium. We hope that some of this e~citement will be conveyed to
the readers of this volume.
J. Drews F.E. Hahn
Vienna Washington
February 1975
Contents
I. RECEPTOR HYPOTHESIS
Structure-Activity Rules and the Receptor Hypothesis
F.E. Hahn 3
Strategy of Drug-Design
W.P. Purcell 15
Physicochemical Factors in Drug-Receptor Interactions
Demonstrated on the Example of the Sulfanilamides
J.K. Seydel 25
Quantitative Structure-Activity Relationships in Drug-Design
A.J. Leo 45
II. DNA AS A DRUG-RECEPTOR
The Ecological Significance of R Factor Activity
E.S. Anderson 59
Structural Constraints in the Binding of Drugs to DNA
M. Waring 77
Molecular Aspects of the Biosynthesis of R Factor DNA
R. Clowes, T. Arai and G. Anderson 91
Elimination of Plasmidic Determinants by DNA-Complexing
Compounds
F.E. Hahn and J. Ciak 99
III. RIBOSOMES AS DRUG-RECEPTORS
Antibiotic Receptor-Sites in Escherichia coli Ribosomes
G. Stoffler and G.W. Tischendorf 117
Altered Methylation of Ribosomal RNA in Erythromycin
Resistant Staphylococcus Aureus
B. Weisblum 145
Binding of Tetracyclines and Other Antibiotics to Ribosomes
H. Kersten 157
Ribosomal Effects of Thiostrepton and Related Antibiotics
E. Cundliffe, J.E. Beven and P.D. Dixon 167
Studies on Active Sites of Ribosomes with Haloacetylated
Antibiotic Analogs
O. Pongs, R. Bald, V.A. Erdmann and E. Reinwald 179
VIII
IV. THE MODE OF ACTION OF CHLORAMPHENICOL
Antibiotic Action on the Ribosomal Peptidyl Transferase
Centre
D. Vazquez, M. Barbacid and R. Fernandez-Munoz 193
Experiments on the Binding Sites and the Action of Some
Antibiotics which Inhibit Ribosomal Functions
R. Werner, A. Kollak, D. Nierhaus, G. Schreiner and
K.H. Nierhaus 217
The Mode of Action of Pleuromutilin as Compared
to Chloramphenicol
G. Hogenauer 235
A Structural Model of the Chloramphenicol Receptor Site
F.E. Hahn and P. Gund 245
V. MICROBIAL ENZYME AS DRUG-RECEPTORS
Spin-Labelled Intermediates as Targets of Antibiotic Action
in Peptidoglycan Synthesis
L.S. Johnston, W.P. Hammes, H.A. Lazar and F.C. Neuhaus 269
Enzyme Inhibitors as Antimicrobial Agents
J.J. Burchall 285
Molecular Mechanism of Action of Rifamycins
G.R. Hartmann 295
LIST OF PARTICIPANTS 301
LIST OF AUTHORS 303
SUBJECT INDEX 305
1. Receptor Hypothesis
Structure-Activity Rules and the Receptor Hypothesis
Fred E. Hahn
I. INTRODUCTION
Chemotherapy as a science began with the postulation of the receptor hypo
thesis by Paul Ehrlich. His famous doctrine, corpora non agunt nisi fixata,
substances do not act unless they are bound, should perhaps today be rephrased
to say, corpora agunt quia fixata, substances do act because they are bound.
Through much of his scientific life, Ehrlich propounded his embattled side chain
theory in order to explain the interaction of chemotherapeutic drugs with
bioreceptors which were still hypothetical. Ehrlich's early observations of
vital staining offered the first visible evidence of selective binding of
chemicals to bioreceptors, and his demonstration, in 1891 (Guttmann and
Ehrlich, 1891), of the therapeutic value of methylene blue in the treatment of
vivax malaria was directly based upon the selective staining properties of this
dye for malarial parasites.
Today, the receptor hypothesis has an established place in the molecular
pharmacology of antimicrobial drugs. The identification of receptors to which
drugs bind is an integral part of any research effort toward the explanation of
mechanisms of action of drugs at the molecular level. With the introduction of
antimetabolite hypothesis (Fildes, 1940) as well as with the recognition of
double-helical DNA as one structurally well-known drug receptor (Lerman, 1963;
Hahn, rev. 1971), knowledge of receptors also has become important to drug
design. Furthermore, the analysis of structure-activity relationships must
differentiate between structural contributions to permeability and electronic
and steric contributions to primary drug action. These last two parameters are
directly related to drug binding to complementary receptor sites.
II. DERIVATION OF RECEPTOR BINDING FROM DOSAGE-RESPONSE CORRELATIONS
Let us assume that a drug A binds to a receptor P in a reversible manner,
obeying the law of mass action. Then it follows that the product of the molar
concentrations of the receptor (P) and of the drug (XA) divided by the molar
concentration of the receptor-drug complex (PXA) equals an equilibrium constant
KA, as shown in equation (I).
(1)
4
If w~ now consider (PT) t~e total recept?r concent~ation and (PXA) the concen
trat10n of receptor to Wh1Ch the drug A 1S bound, 1t follows that the differ
ence (PT - PXA) represents the concentration of free receptor. Substituting
this into equation (I) one obtains equation (II).
(PT - PXA) (XA)
(II )
(PXA)
which can be rearranged into equation (III)
(III)
When the concentration (PXA) of the receptor-drug complex is isolated one
obtains equation (IV)
(PT) (XA)
(PXA) = (IV)
KA + (XA)
This is the familiar Langmuir adsorption isotherm in which the concentration of
the complex equals zero for drug concentration zero and approaches the total
receptor concentration (PT) when the drug concentration (XA) becomes very large.
If one then makes the assumption that quantified biological responses to
graded concentrations of a drug are proportional to the fractions of the
receptor occupied by the drug, a plot of the dosage-response correlation should
obey equation (IV).
For example, in 1956 we published precise dosage-response determinations
of the decreases of growth rates of Escherichia coli by graded concentrations
of chloramphenicol (Hopps, Wisseman, Hahn, Smade~d Ho, 1956). At that time,
we only knew that the antibiotic was bacteriostatic, i.e. that its antibacterial
action was reversible, and that chloramphenicol was a specific inhibitor of
protein biosynthesis. But neither transfer RNA, nor ribosomes, nor messenger
RNA, nor incorporation factors had been discovered, and the mechanism of protein
biosynthesis was still a typical "black box problem" in which one can measure
input and output but does not know the mechanics inside the box.
100
10 00760.156 0.312 0.625 1.25 2.5 5 10
CONCENTRATION ~gfml CONCENTRATION ~gfml
Fig. 1. Dosage-response correlation for inhibition of growth of Escherichia
coli C2 by chloramphenicol.