HOW DO ENZYMES WORK

Consider the thermodynamic cycle that relates substrate binding to transition-state binding  

The upper pathway represents the uncatalyzed reaction the lower pathway represents the enzyme-catalyzed reaction. Pour equilibrium constants can be written for the scheme (2.1)  

The ratio of the equilibrium constants for conversion of substrate from the ground state to the transition state in the presence and absence of enzyme is related to the ratio of the dissociation constants for ES and ES complexes  

As discussed in Chapter 1, absolute reaction rate theory predicts that the rate constant of a reaction kr) is directly proportional to the equilibrium 

Relative changes in reaction rates due to enzyme catalysis are given by the ratio of reaction rates for the conversion of substrate to product in the presence ke) and absence (ku) of enzyme  

---

How Do Enzymes Work Citrate Synthase 1043 Focus On... The Protein Data Bank 1048... 

Antibodies that demonstrate catalytic activity. The early development of these antibodies was based on the use of haptens, which mirrored transition state intermediates for enzyme-catalyzed reactions. Catalytic antibodies can be referred to as abzymes. See Kraut, J., How do enzymes work Science 242, 533-540, 1988 Lemer, R.A. and Tramontano, A., Catalytic antibodies, Sci. Am. 258, 65-70, 1988 Green, B.S., Catalytic antibodies and biomimetics, Curr. Opin. Biotechnol. 2, 395 400,1991 Jacobs, J.W., New perspectives on catalytic antibodies. Biotechnology 9, 258-262, 1991 Blackburn, G.M., Kingsbury, G., Jayaweera, S., and Burton, D.R., Expanded transition state analogues, Ciba Found. Symp. 159, 211-222, 1991 O Kennedy, R. and Roben, R, Antibody engineering an overview. Essays Biochem. 26, 59-75, 1991 Stewart, J.D., Krebs, J.F., Siuzdak, G. et al.. Dissection of an antibody-catalyzed reaction, Proc. Natl. Acad. Sci. USA 91,7404-7409,1994 Posner, B., Smiley, J., Lee, 1., andBenkovic,... 

How Do Enzymes Work Citrate Synthese 1045 Table 26.3 Structures of Some Common Coenzymes (continued)... 

Enzymes play a vital role in the majority of biochemical reactions. Not only do they allow for life as we know it, they demonstrate remarkable specificity in many cases. How do enzymes work on only one chemical process, whereas hundreds of perhaps similar processes occur in the same general vicinity Protein structure in general provides the answers. The primary, secondary, and tertiary structnres of a protein all serve to direct the specific activity of an enzyme, but the region where the specific reaction is catalyzed is referred to as the active site. 

Kraut, J., 1988. How do enzymes work Sdence 242 533-540. Waxman, D. J., and Strominger, J. L., 1983. Penicillin-binding proteins and the mechanism of action of (3-lactam antibiotics. Annu. Rev. 

Kraut, J. How Do Enzymes Work Science 242, 533-540 (1988). [An advanced discussion of the role of transition states in enzymatic catalysis.]... 

---