Enzymology and Molecular Biology

Although each of these disciplines could be discussed separately, for the contemporary biotransformation scientist these areas are intimately intertwined. Since biotransformations are enzyme mediated, complete understanding of xenobiotic disposition is only achieved when one also considers the role and impact of the individual enzymes involved. 

Enzymological techniques allow the study of individual enzymatic reactions as well as the role of individual enzymes in complex systems. Each of the questions What happens What enzymes contribute How does it happen will require separate techniques. It is not unusual to ask and answer these questions in a very short period of time. This obviously requires a certain degree of breadth, versatility, and flexibility along with a fundamentally strong understanding of the literature. 

Cells and subcellular fractions from humans and many preclinical species are readily available. These reagents make it possible to make interspecies extrapolations easily. At one time, a major reason cited for early drug attrition was pharmacokinetic failure, attributable to the difficulty in extrapolating pharmacokinetic behavior from animals to humans. In this author s experience, unexpected pharmacokinetic performance in humans is now a rare event. In addition, it is now commonplace to obtain very mechanistic information revealing the probability of observing quite specific molecular events (e.g., toxicity) in humans (Mutlib et ah, 2000). 

While the availability of trans-species enzyme systems has had a major impact, advances in molecular biology have also enabled the query of increasingly sophisticated questions. Molecular biological methods have made it possible to clone and express enzymes to study reactions at a molecular level. This has improved our ability to study enzyme reactions at a fine molecular level, to discern the contributions of individual enzymes in complex systems, and even to employ them as bioreactors to generate small quantities of metabolite standards. 

The basis for many metabolizing enzyme polymorphisms is becoming better understood, allowing one to anticipate potential interindividual disposition differences. Molecular biological techniques have defined the basis for polymorphisms and have described the distribution of the variants in a population. It is now quite easy to discern whether a drug may behave differently in one individual compared to another and to even exclude anticipated poor responders from trials in a controlled fashion (Murphy et al., 2000). 

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Enzymology and molecular biology of aflatoxin biosynthesis 97CRV2537. 

Cormier, M. J., Prasher, D. C., Longinaru, M., and McCann, R. O. (1989). The enzymology and molecular biology of the calcium-activated photoprotein, aequorin. Photochem. Photobiol. 49 509-512. 

Kappler U, Dahl C. 2001. Enzymology and molecular biology of prokaryotic sulfite oxidation. FEMS Microbiol Lett 203 1-9. 

Varin, L., Elavonoid sulfation phytochemistry, enzymology and molecular biology. Rec. Adv. Phytochem., 26, 233, 1992. 

Dixon, R.A., Dey, P.M. Lamb, C.J. (1983). Phytoalexins enzymology and molecular biology. Advances in Enzymology and Related Areas of Molecular Biology 55, 1-135. 

Minto RE and Townsend CA (1997) Enzymology and molecular biology of aflatoxin biosynthesis. Chem Rev 97, 2537-2555. 

Abell C (1999) Enzymology and molecular biology of the shikimate pathway. Comprehensive Natural Products Chemistry, Vol 1. Elsevier, Amsterdam, pp 573-607. 

Hashimoto T. (1996) Peroxisomal beta-oxidation enzymology and molecular biology. Ann. N. Y. Acad. Sci. 804, 86-98. 

Weiner H, Lindahl R, Crabb DW, Flynn TG. Enzymology and Molecular Biology of Carbonyl Metabolism 6. New York, London Plenum Press, 1997 1-602. 

VARIN, L., Flavonoid sulfation Phytochemistry, enzymology and molecular biology, in Phenolic Metabolism in Plants (H.A. Stafford, R.K. Ibrahim, eds.), Plenum Press, New York. 1992, pp. 233-254. 

Kutchan, T.M., Dittrich, H., Bracher, D. and Zenk, M.H. (1991) Enzymology and molecular biology of alkaloid biosynthesis. Tetrahedron, 47,5945-54. 

Biosynthesis of dhurrin in sorghum plays an important role as a model system for obtaining further insight into the enzymology and molecular biology of the biosynthesis of cyanogenic glucosides. 

Uotila, L., and Koivusalo, M, (1996), Expression of formaldehyde dehydrogenase and S-formylglutathione hydrolase activities in different rat tissues, h "Enzymology and Molecular Biology of Carbonyl Metabolism," Vol. 6 (H, Weiner, R. Lindahl, D. Crabb, and T. Ejim, eds.), pp. 365-371. Plenum, New York. 

Okuda, K., Usui, E, and Ohyama, Y. (1995). Recent progress in enzymology and molecular biology of enzymes involved in vitamin D metaboEsm. /- Lipid Res. 36,1641-1652. 

George, S.G. Enzymology and molecular biology of phase II xenobiotic-conjugating enzymes in fish. In Aquatic Toxicology Molecular, Biochemical and Cellular Perspectives, edited by D.C. Malins and G.K. Ostrander, Boca Raton, FL, Lewis Publishers, pp. 37-85, 1994. 

Ueda N, Katayama K, Kurahashi Y, Suzuki M, Suzuki H, Yamamoto S, Katoh I, Di Marzo V, and De Petrocellis L (1999) Enzymological and molecular biological studies on anandamide amidohydrolase. Adv Exp Med Biol 469. 513-518. 

ENZYMOLOGY AND MOLECULAR BIOLOGY OE CARBONYL METABOLISM 7 Edited by Henry Weiner, Edmund Maser, David W. Crabb, and Ronald Lindahl... 

Minto RE, Townsend, CA (1997) Enzymology and Molecular Biology of Aflatoxin Biosynthesis. Chem Rev 97 2537... 

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