Photoaffinity labels for enzymes capable of binding glutathione or its disulphide

The syntheses and photolyses of several glutathione analogues incorporating aryl azide moieties on the N-terminus or SH sites are described. Such labels include S-blocked glutathiones, N,S-blocked glutathiones and an N,N′-blocked glutathione disulphide. S-(4-Azidophenacyl)glutathione has been used to label covalently yeast glyoxalase I, beef liver glyoxalase II, and glutathione-S-transferase; N,S-bis(4-azidobenzoyl)glutathione has been used to label covalently formaldehyde dehydrogenases from Pseudomonas species and beef liver; N,N′-bis-(4-azidobenzoyl)glutathione disulphide has been successfully used to label covalently yeast glutathione reductase.