You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Partial Purification and Characterization of Cystine Lyase from Cabbage (Brassica oleracea var capitata)
David I. Hall and Ivan K. Smith
Vol. 72, No. 3 (Jul., 1983), pp. 654-658
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/4268089
Page Count: 5
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Cabbage (Brassica oleracea var capitata) leaves were used as a source of cystine lyase. Diethylaminoethyl-cellulose chromatography resolved two peaks of activity, designated I and II. Cystine lyase I (molecular weight 145,000) and O-acetylserine sulfhy-drylase (molecular weight 70,000) were resolved by Bio-Gel A-0.5M chromatography. This isozyme catalyzed an α,β-elimination reaction with cystine, cysteine, O-acetylserine, and several S-substituted cysteines. The substrate specificity was similar to previously reported S-alkylcysteine lyases. The elution profiles during purification, and heat inactivation studies indicated that the above reactions were catalyzed by a single protein. The pH optimun with cystine and cysteine as substrate was 8.5 to 9.0, and the Km values were: cystine (0.3 mM), cysteine (0.3 mM), O-acetylserine (6 mM), and S-methylcysteine sulfoxide (1.8 mM). Cystine lyase II was resolved into three peaks (molecular weight greater than 500,000, 240,000, and 145,000) using Bio-Gel A-0.5M chromatography. This enzyme degraded L-cystine, L-cysteine, O-acetylserine, S-methylcysteine sulfoxide, and djenkolic acid. The pH optimum with cystine and cysteine was 8.5 to 9.0, and the Km values were: cystine (0.3 mM), cysteine (0.3 mM), O-acetylserine (12.5 mM), and S-methylcysteine sulfoxide (3.7 mM).
Plant Physiology © 1983 American Society of Plant Biologists (ASPB)