Enzymes are polypeptide macromolecules that catalyse, or speed up, all biochemical reactions.
Keywords: enzymes; protein structure; enzyme catalysis; RNA catalysis; active site; coenzymes
Enzymes: General Properties
Timothy DH Bugg, University of Warwick, Coventry, UK
Published online: April 2001
DOI: 10.1038/npg.els.0000709
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Figure 1. Reaction catalysed by fructose-1,6-bisphosphate aldolase and hexokinase.
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Figure 2. Free energy profiles for (a) an acid-catalysed reaction, (b) an enzyme-catalysed reaction. S = substrate; P = product; ES = enzyme–substrate complex; E.Int = enzyme–intermediate complex; EP = enzyme–product complex.
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Figure 3. Schematic representations of (a) an enzyme active site; (b) an enzyme–substrate (ES) complex; (c) an ES complex with cofactor (Z).
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Figure 4. Schematic representation of an enzyme-catalysed hydrolysis reaction. The symbol ‡ indicates the transition state for the reaction. Note the stabilization of the enzymatic transition state by hydrogen bonding, indicated by dashed lines.
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Figure 5. Self-splicing reaction carried out by Tetrahymena group I intron.
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Figure 6. (a) The general structure of an l-amino acid; (b) structure of the N-terminal portion of a polypeptide chain (sequence Met-Ala-Ile-Asp-Ser); (c) the folding of a polypeptide chain.
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Figure 7. (a) Posttranslational cleavage of a propeptide; (b) schematic representation of effector binding.
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| Further Reading | |
| book Abeles RH, Frey PA and Jencks WP (1992) Biochemistry. Boston: Jones & Bartlett. | |
| book Branden C and Tooze J (1991) Introduction to Protein Structure. New York: Garland. | |
| book Bugg TDH (1997) An Introduction to Enzyme and Coenzyme Chemistry. Oxford: Blackwells Science. | |
| book Stryer L (1981) Biochemistry. San Francisco: Freeman. | |
| book Walsh CT (1979) Enzymatic Reaction Mechanisms. San Francisco: Freeman. | |
| book Wong CH and Whitesides GM (1994) Enzymes in Synthetic Organic Chemistry. Oxford: Pergamon. | |
