Enzymological mechanistic

Lusong Luo, Enzymology Mechanistic Pharmacology, GlaxoSmithKline Pharmaceuticals, 1250 S. Collegeville Road, Collegeville, PA 19426... 

The versatile chemistry of pyridoxal phosphate offers a rich learning experience for the student of mechanistic chemistry. William Jencks, in his classic text. Catalysis in Chemistry and Enzymology, writes ... 

Fellow at St John s College and was awarded the Humphreys Research prize. At Cambridge, Nigel was a Research Fellow of the Royal Commission for the Exhibition of 1851 and Royal Society University Research Fellow. He was elected a Fellow of the Royal Society of Chemistry in 1997. Aged 36, Nigel is now Professor at Leicester University and Lister Institute Research Fellow. He is a recipient of the Colworth Medal of the Biochemical Society. His scientific interests include mechanistic and quantum enzymology his recreational interests include Victorian and College philately. 

The great power of mechanistic enzymology in drug discovery is the quantitative nature of the information gleaned from these studies, and the direct utility of this quantitative data in driving compound optimization. For this reason any meaningful description of enzyme-inhibitor interactions must rest on a solid mathematical foundation. Thus, where appropriate, mathematical formulas are presented in each chapter to help the reader understand the concepts and the correct evaluation of the experimental data. To the extent possible, however, I have tried to keep the mathematics to a minimum, and instead have attempted to provide more descriptive accounts of the molecular interactions that drive enzyme-inhibitor interactions. 

Structure and Function of Peptidyl Carrier Protein Domains Structure and Function of Adenylation Domains Structure and Function of Condensation Domains Structure and Function of Thioesterase Domains Multidomain NRPS Structural Information PCP-C didomain structure PCP-TE didomain structure Structure of a C-A-PCP-TE termination module Pathways to Nonproteinogenic Amino Acids Incorporated into NRP Natural Nonproteinogenic Amino Acids Present as Cellular Metabolites Modification of Proteinogenic Amino Acids Nonproteinogenic Amino Acids Derived from Multistep Pathways Tailoring Enzymology in NRP Natural Products Chemical Approaches Toward Mechanistic Probes and Inhibitors of NRPS... 

Powerful mechanistic enzymology in conjunction with structural biology studies have provided insight into the manner in which the protein environment of an apoenzyme augments and controls coenzyme reactivity. The goal of the protein design efforts that include coenzyme functionality is to estabhsh whether these features can be emulated within designed peptide and protein constructs. 

Significant advances have been made in the preparation of discrete macromolecules that include both coenzyme function and a defined polypeptide or protein architecture. Preliminary, but promising, functional studies have been carried out and assay methods developed. While in many cases rather modest effects have been observed, what is significant is that the methodology exists to prepare, characterize, and study defined macromolecular constructs. With new information becoming available on co enzyme-dependent protein catalysts from structural biology and mechanistic enzymology, it should be possible to more fully exploit the remarkable breadth of coenzyme reactivity in tailored synthetic systems. 

Midelfort and Rose made a major advance in mechanistic enzymology through their development of an isotope... 

Nevertheless, the full-blown mechanism that showed the role of the coenzyme was only written out in detail by Braunstein and M. M. Shemyakin in 1953 (Braunstein and Shemyakin, 1952, 1953). Their formulae (2), complete with the curved arrow notation of physical organic chemistry, clearly pointed out the role of the coenzyme as an electron sink in a ketimine mechanism. They showed how the coenzyme can function in transamination, racemization and, with some help from Hanke and his collaborators (Mandeles et al 1954), in decarboxylation. The mechanisms they advanced were exactly what we would postulate today, and constituted an early and successful application of theory to mechanistic enzymology. But it must be admitted that the theory appealed because it was reasonable the authors had little or no evidence, in terms of physical organic chemistry, to support their formulation, which is shown in part below. 

The mechanism of the reaction is outlined in Scheme 6. In order to release ammonia or an amino-acid from an amide or peptide, the leaving group must be protonated, perhaps by the histidinium ion that is formed when the proton is removed from the hydroxyl group of the serine residue. This level of detail in the mechanism, however, was not seriously considered in the early days of mechanistic enzymology. 

Obviously, the work reported here constitutes only a part of the great body of research on mechanistic enzymology from the years 1947 to 1963. But they constitute the major part of the history, that is to say, the major discoveries that stimulated the field. 4... 

Mechanistic enzymology has developed at a rapid pace since 1963, and the artificial catalysts of which Fischer spoke in 1902 appear within the realm of possibility (Breslow, 1982). Enzymologists now have reasonable notions of mechanism and of the factors needed to achieve rapid rates and specificity. Nevertheless, the foundations for mechanism and to some extent for an understanding of the factors relevant to enzymology were laid down in the years 1947-1963. By the end of that time, enzymology had become incorporated into physical organic chemistry. 

Makris TM, Davydov R, Denisov IG, et al. Mechanistic enzymology of oxygen activation by the cytochromes p450. Drug Metab Rev 2002 34 691-708. 

There is considerable interest in the design of highly specific irreversible enzyme inhibitors because of their potential use as therapeutic agents. Part of the research program of most pharmaceutical companies is the rational design of drugs based on mechanistic ideas from enzymology, biochemistry, and chem-... 

The qualitative description of enzyme catalysis In terms of the TS theory (Pauling, 1, 2) that the enzyme Is complementary to an unstable molecule with only transient existence namely, the activated complex (ES ) for which the power of attraction by the enzyme Is much greater than that of the substrate Itself has been discussed energetically (8) and mechanistically (10,22-25). Pauling s assertion has opened a new era In enzymology, and relevant to our discussion Is the stabilization of the activated complex and TSA as powerful enzyme inhibitors. As the transition state Is a mathematical construction (with a typical half-life of 10 1 msec.,... 

Other reviews have summarized many of the apparent biological functions of the stress-70 proteins (Craig et ai, 1990, Gething and Sambrook, 1992 Haas, 1991 Winfield and Jarjour, 1991). This review focuses primarily on the protein chemistry and mechanistic enzymology of this protein family. 

In recent years kinetic and mechanistic studies have been done on the copper oxidases. Recent work has concentrated on laccase and tyrosinase, and since these two enzymes are good examples of the complexities involved, the rest of this paper concentrates on the enzymology of these two proteins. They also give rise to interesting comparisons since they have some substrates in common (e.g., catechol) but differ in certain aspects of their physicochemistry and mechanism. 

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