Purification and characterization of Clostridium sticklandii D-selenocystine alpha, beta-lyase.
We have found a novel enzyme that decomposes D-selenocystine into pyruvate, ammonia, and elemental selenium in extracts of Clostridium sticklandii and C. sporogenes. The enzyme of C. sticklandii has been purified to homogeneity. It has a molecular weight of 74,000 and consists of two subunits identical in molecular weight (35,000). Pyridoxal 5'-phosphate is required as a cofactor. In addition to D-selenocystine, D-cystine, D-lanthionine, meso-lanthionine, and D-cysteine serve as substrates. However, D-selenocysteine, D-serine, DL-selenohomocystine, and L-amino acids are inert. The enzyme also catalyzes the beta-replacement reaction between D-selenocystine and a thiol to produce S-substituted D-cysteine. L-Selenohomocysteine also can serve as a substituent donor in the beta-replacement reaction to yield selenocystathionine.
Esaki
N
N
Institute for Chemical Research, Kyoto University, Japan.
Seraneeprakarn
V
V
Tanaka
H
H
Soda
K
K
D055598:Chemical Phenomena; D002621:Chemistry; D003013:Clostridium / Q000201:enzymology*; D003553:Cystine / Q000031:analogs & derivatives* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007118:Immunoassay; D008190:Lyases / Q000302:isolation & purification* / Q000378:metabolism; D016566:Organoselenium Compounds; D012643:Selenium / Q000378:metabolism*; D013379:Substrate Specificity
D016566:Organoselenium Compounds; C009226:selenocystine; D003553:Cystine; D008190:Lyases; C054740:D-selenocystine alpha, beta-lyase; D012643:Selenium