Chemistry International
Vol. 21, No. 6
November 1999
37th
IUPAC Congress-27th GDCh General Meeting
14-19 August 1999,
Berlin, Germany
This extremely successful event, held at Berlin's International Congress
Center (ICC) with the general theme "Frontiers in Chemistry: Molecular
Basis of the Life Sciences", celebrated the 80th anniversary
of the founding of IUPAC and the 50th anniversary of the
refounding of the Gesellschaft Deutscher Chemiker (GDCh) after World
War II. More than 2 400 participants (most from outside Germany) from
55 countries had the opportunity to attend about 350 talks (in up to
12 parallel sessions) and to view about 1 200 posters. Over 250 attendees
from developing or economically disadvantaged countries were sponsored,
at least in part, by substantial reductions in registration fees.
Prof.
Dr.
Thomas R. Cech
|
Eight plenary lecturers, including four Nobel Prize winners,
headlined an array of leading chemists from around the world reporting
on their latest research findings in medicine, agriculture, nutrition,
and the environment. The first plenary speaker, Prof. Dr. Thomas R.
Cech (1989 Nobel Prize winner) of the Department of Chemistry and Biochemistry,
University of Colorado, Boulder, CO, USA, discussed "RNA in Catalysis:
Ribozymes and Telomerase". He showed how some RNA molecules called
ribozymes fold to form active sites for biochemical reactions in the
complete absence of proteins, while other cellular catalysts are ribonucleoprotein
(RNP) particles that contain essential protein and RNA components. He
used as an example the crystal structure of the Tetrahymena ribozyme
to show how RNA can fold to form a preorganized active site, much like
a protein enzyme. His recent work has extended the scope of RNA catalysis
via use of in vitro selection-amplification and a combinatorial
library of RNA sequences to find ribozymes that catalyze (106-fold)
peptidyl transfer between aminoacyladenosine and a second amino acid.
He also demonstrated how the RNP enzyme telomerase, responsible for
synthesizing the ends of chromosomes in eukaryotes, is attracting much
attention because of its roles in cellular immortality and in cancer.
Prof. Cech's work combines genetic and biochemical approaches to improve
our understanding of RNP enzymes.
Prof.
Dr.
Stephen J. Lippard
|
Prof. Dr. Stephen J. Lippard of the Department of Chemistry,
Massachusetts Institute of Technology, Cambridge, MA, USA, spoke on
"The Chemistry of Selective Hydrocarbon Oxidation in Bacteria".
He described how methanotrophic bacteria use a soluble methane monooxygenase
(sMMO) system of proteins to convert methane selectively to methanol
in the first chemical step required for carbon assimilation and energy
via the reaction CH4 + O2 + NADH + H+ !
CH3OH + H2O + NAD+. His laboratory
is engaged in an extensive program to understand all aspects of this
reaction through studies of sMMO from Methylococcus capsulatus
(Bath) as well as through the synthesis and characterization of synthetic
model compounds. Prof. Lippard's work has employed X-ray crystallography
and high resolution NMR spectroscopy to elucidate the structures of
the enzymes and proteins involved. Depending on the relative concentrations
of the regulatory protein, reductase, and hydrocarbon substrate, the
sMMO system can function alternatively as an oxidase or hydroxylase.
From analysis of steady state kinetic and isothermal titration calorimetry
data, Prof. Lippard has proposed a model in which the reductase and
coupling protein bind noncompetitively at distinct interacting sites
on the hydroxylase during catalysis.
Prof.
Dr. Roald Hoffman (left) receives an Honorary Membership from
Prof. Dr. Erhard Meyer-Galow, President of the German Chemical
Society (Gesellschaft Deutscher Chemiker).
|
Prof. Dr. Roald Hoffman (1981 Nobel Prize winner) of the Department
of Chemistry, Cornell University, Ithaca, NY, USA, after being made
an Honorary Member of the GDCh, delivered a disarmingly delightful lecture
entitled "Chemistry in Culture, Culture in Chemistry". In
a five-minute introduction presented entirely in German, he declaimed
quite movingly that despite having lost three grandparents and his father
to the Holocaust by the time he arrived in the United States at the
age of eleven, he bears no animosity about the past. This artist, poet,
author, andabove allsuperb exponent of applied, theoretical, organic,
inorganic, and solid state chemistry then spoke in a most accessible
manner of the need for chemists to build bridges to the general public.
It is so important, he said, for chemists to teach as widely as possibleand
not just in schoolsbecause chemical research is fundamentally about
change, and people are at best ambivalent about change and at worst
afraid of it. He amplified his point with many fascinating historical
examples, most notably the platinum catalyst lamp, designed by Johann
Wolfgang Döbereiner (1780-1849), which provided a significant amount
of indoor lighting for central Europe during the second quarter of the
19th century. Prof. Hoffmann pointed out that papers about
the chemistry of the Döbereiner lamp are still being published
today. He also spoke of author-philosopher-poet Johann Wolfgang von
Goethe's fascination with chemistry, a topic discussed in more detail
in an evening Congress lecture by Prof. Dr. Georg Schwedt, who has written
a book on the subject. Prof. Hoffman reminded us that the cultural dimension
of chemistry is just as important as the science, and that both must
be communicated effectively to the public if chemistry is to prosper.
Prof.
Dr.
Heinz A. Staab
|
Prof. Dr. Heinz A. Staab of the Department of Organic
Chemistry, Max-Planck-Institut, Heidelberg, Germany, a past president
of the GDCh (1984-1985), also was made an Honorary Member before delivering
his plenary lecture. He spoke in detail about "Quinone-Porphyrin
Interactions". His presentation elucidated the photosynthetic reaction
mechanisms of porphyrin donors and quinone acceptors, with many examples
of structures and visible absorption spectra.
Prof.
Dr.
Sir John E. Walker
|
Prof. Dr. Sir John E. Walker (1997 Nobel Prize winner)
spoke about "How ATP is Made" in the annual Federation of
European Chemical Societies (FECS) lecture. His pioneering work on ATP
(adenosine triphosphate) synthase, begun in the early 1980s with the
aim of ascertaining its detailed chemical structure, has had a significant
impact upon the chemical and biological sciences. With Paul Boyer and
Jens Skou, he won the 1997 Nobel Prize for Chemistry for his "elucidation
of the enzymatic mechanism underlying the synthesis of ATP". Prof.
Walker graphically illustrated the importance of ATP synthesis by pointing
out that we turn over approximately our entire body weight in ATP every
24 hours. The complexity of the effort in elucidating the structure
of the enzyme is apparent from Prof. Walker's demonstration that bovine
F1-ATPase consists of nine polypeptide chains with a total
molecular weight of 371 765, with each of the substituent chains ranging
in molecular weight from 5 652 to 55 264.
Prof.
Dr.
Martin Karplus
|
Prof. Dr. Martin Karplus of the Laboratoire de Chimie
Biophysique, Université Louis Pasteur, Strasbourg, France (and
Research Professor in the Department of Chemistry and Chemical Biology,
Harvard University, Cambridge, MA, USA) gave a plenary lecture on "Protein
Dynamics: From Femtoseconds to Milliseconds". He presented a brief
overview of the use of simulations for studying protein dynamics and
presented three examples that involved dynamic phenomena on time scales
ranging from femtoseconds to milliseconds. Prof. Karplus described the
behavior of the protein and the CO ligand after photodissociation of
the myoglobin CO complex. He has investigated catalysis by the enzyme
triosephosphate isomerase of the transformation of dihydroxyaldehyde
phosphate to glyceraldehyde phosphate, and his work has shown how the
enzyme reduces the activation barrier. Prof. Karplus compared the classical
dynamics of the reaction in the enzyme with the results expected from
transition state theory. His laboratory has employed simulations to
determine some general principles of protein folding.
Prof.
Dr.
Chi-Huey Wong
|
Prof. Dr. Chi-Huey Wong of the Department of Chemistry
and the Skaggs Institute for Chemical Biology, The Scripps Research
Institute, La Jolla, CA, USA spoke on "Chemical-Enzymatic Synthesis
and Glycobiology". He pointed out that of the three major classes
of biomoleculesproteins, nucleic acids, and carbohydratesit is carbohydrates
that are the least exploited. Despite the important roles that saccharides
play in numerous biological recognition events (e.g., bacterial and
viral infection, cancer metastasis, and inflammatory reactions), the
pace of development of carbohydrate-based therapeutics has been relatively
slow. Prof. Wong suggested that this slow pace is further hindered by
the lack of practical synthetic and analytical methods available for
carbohydrate research and by the problems associated with undesirable
properties of carbohydrates as drug candidates. He showed how recent
advances in the field, however, have demonstrated that many of these
problems can be circumvented with the use of chemo-enzymatic synthetic
methods and carbohydrate mimetics, i.e., small molecules that contain
the essential functional groups (often with additional hydrophobic or
charged groups) to resemble the active conformation of the parent structure.
Prof.
Dr.
Robert Huber
|
Prof. Dr. Robert Huber (1988 Nobel Prize winner) of the
Max-Planck-Institut für Biochemie, Martinsried, Germany delivered
the final plenary lecture at the closing session of the Congress. His
topic was "Biomolecular Cages for Protein Folding and for Protein
Degradation". He demonstrated how recent crystal structural studies
of the Thermosome, an archaeal homolog of the eukaryotic chaperonin
CCT, of the yeast 20S proteasome, and of the E. coli HsIV protein,
provide detailed views of the subunit structures and arrangements of
these large homo- or hetero-oligomeric complexes. All three complexes
observed are closed in their respective crystal forms, and the cavities
are quite inaccessible from the outside such that substantial rearrangement
of segments, domains, or subunits is required for macromolecular substrate
entry and binding. Prof. Huber showed that binding of ATP and its analogs
induces small local changes and large domain rotations in the thermosome,
possibly representing intermediates between closed and open forms in
the catalytic cycle, but leaves the overall conformation closed in all
crystal forms studies. He pointed out how very detailed structural information
is available for proteolysis by the proteasome through small substrate
binding studies and mutagenesis experiments that explain the specificity,
processivity, and preferred length distribution of its peptide products.