Biochemical and immunochemical characterization of Brassica juncea glyoxalase I

A homogenous preparation of glyoxalase I (S-lactoylglutathione-lyase, EC 4. 4.1.5) was obtained from Brassica juncea seedlings. The enzyme is a heterod imer with 27,000 and 29,000 M-r subunits and native M-r of 56,000. The circ ular dichroic spectra of the protein showed characteristics of a distinctly helical protein, and magnesium affected the secondary structure. It is a z inc metalloenzyme. Amino acid modification studies suggested the involvemen t of histidine residues in catalysis. Apo-glyoxalase I was reactivated by d ivalent cations Mn2+ (0.5 Mm) > Mg2+ (5 Mm) > Zn2+ (0.05 Mm) and Ca2+ (0.01 Mm). Monospecific, polyclonal anti-glyoxalase I antibodies were raised, wh ich showed its presence in seeds, roots, hypocotyl, cotyledon and different flower parts. They showed varied degree of cross reactivity with the extra cts from various plants, yeast, bacteria and animal system. (C) 1998 Elsevi er Science Ltd. All rights reserved.