Purification and Characterization of Cystine Lyase a from Broccoli Inflorescence

Article abstract of DOI:10.1271/bbb.61.1890

One of the three isoforms of an enzyme degrading L-cystine was purified to homogeneity from broccoli (Brassica oleracea var. italica) inflorescences, with use of a sensitive assay based on derivatization of a reaction product with monobromobimane. The reaction product with a thiol group was found to be thiocysteine from results of liquid chromatography-mass spectrometry and high-resolution mass spectrometry. Pyruvate was also a reaction product, formed in equimolar amounts. The purified enzyme catalyzed β-elimination of L-cystine to yield thiocysteine, pyruvate and possibly ammonia, so it was cystine lyase a. L-Cystine but not D-cystine was a substrate of the enzyme. S-Methyl L-cysteine sulfoxide and S-ethyl L-cysteine sulfoxide were substrates but were less suitable than L-cystine. L- and D-cysteine and also cystathionine were not substrates. The purified enzyme (M_r 186,000) was composed of four identical subunits (M_r 45,000) and was pyridoxal 5′-phosphate-dependent.

Full text of DOI:10.1271/bbb.61.1890

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Bioscience, Biotechnology, and Biochemistry
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Purification and Characterization of Cystine Lyase a
from Broccoli Inflorescence
Koji Ukaia & Jiro Sekiyaa
a Division of Applied Life Sciences, Graduate School of Agricultural Sciences, Kyoto
University, Kyoto 606–01, Japan
Published online: 12 Jun 2014.
To cite this article: Koji Ukai & Jiro Sekiya (1997) Purification and Characterization of Cystine Lyase a from Broccoli
Inflorescence, Bioscience, Biotechnology, and Biochemistry, 61:11, 1890-1895, DOI: 10.1271/bbb.61.1890
To link to this article: http://dx.doi.org/10.1271/bbb.61.1890
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