Enzymes: General Properties


Enzymes are polypeptide macromolecules that catalyse, or speed up, all biochemical reactions.

Keywords: enzymes; protein structure; enzyme catalysis; RNA catalysis; active site; coenzymes

Figure 1.

Reaction catalysed by fructose‐1,6‐bisphosphate aldolase and hexokinase.

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.

Figure 3.

Schematic representations of (a) an enzyme active site; (b) an enzyme–substrate (ES) complex; (c) an ES complex with cofactor (Z).

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.

Figure 5.

Self‐splicing reaction carried out by Tetrahymena group I intron.

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.

Figure 7.

(a) Posttranslational cleavage of a propeptide; (b) schematic representation of effector binding.


Further Reading

Abeles RH, Frey PA and Jencks WP (1992) Biochemistry. Boston: Jones & Bartlett.

Branden C and Tooze J (1991) Introduction to Protein Structure. New York: Garland.

Bugg TDH (1997) An Introduction to Enzyme and Coenzyme Chemistry. Oxford: Blackwells Science.

Stryer L (1981) Biochemistry. San Francisco: Freeman.

Walsh CT (1979) Enzymatic Reaction Mechanisms. San Francisco: Freeman.

Wong CH and Whitesides GM (1994) Enzymes in Synthetic Organic Chemistry. Oxford: Pergamon.

This article was reviewed by the editors in 2013 and was found to still be up to date.

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Bugg, Timothy DH(Apr 2001) Enzymes: General Properties. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0000709]