Terms and Definitions - The Bio Dialect

Enzymes are made from just 20 a-amino acid building blocks (structures and abbreviations are shown in Table 5.1). Each amino acid has a unique side chain, or residue, which can be polar, aliphatic, aromatic, acidic, or basic. The amide bonds (peptide bonds) make up the enzyme s backbone, and the residues determine the ultimate structure and catalytic activity of the enzyme. When the sequence of amino acids (the primary structure) for an enzyme is assembled in vivo, it folds 

Enzymology has its own terminology. Reactants and reagents are generally referred to as substrates. Some enzymes only function when bound to additional, non-protein species. These helpers are called cofactors. The combination enzyme + cofactor is called a holoenzyme, while an enzyme that is missing its cofactor is called an apoenzyme. Cofactors can be either inorganic (e.g., metal ions) or organic. If 

Enzyme class Enzyme function (reactions catalyzed) 

2 Transferases transfer of a functional group from one molecule to another 

4 Lyases adding or removal of a group to form a double bond, or addition of a group to a double bond 

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