THE 30 KDA PROTEIN COPURIFIED WITH CHICK LIVER GLUTATHIONE S-TRANSFERASES IS A CARBONYL REDUCTASE

An unidentified 30 kDa protein was co-purified with chick liver glutat hione S-transferases from S-hexylglutathione affinity column. The prot ein was isolated to apparent homogeneity with chromatofocusing. The mo lecular mass of the protein was determined to be 30277 +/- 3 dalton by mass spectrometry. The protein was digested with Achromobacter protei nase I. Amino-acid sequence analyses of the resulting peptides show a high degree of identity with those of human carbonyl reductase. The pr otein is active with menadione as substrate. Thus, it is identified as chick liver carbonyl reductase.