Spinach threonine dehydratase. Inhibition by L-cysteine and D-cysteine.
L-threonine deaminase from spinach is inhibited by D- and L-cysteine. The inhibition patterns by D-cysteine and by L-cysteine are non-competitive. The value of Ki for D-cysteine and L-cysteine is of the same order of magnitude. Inhibitions by L-isoleucine and L-cysteine are additional. These results indicate that inhibition by L-cysteine occurs on a site of enzyme which is different from the binding site for L-isoleucine and L-valine. Probably L-cysteine and D-cysteine form the thiazolidinic ring with a PLP mole. Which is not costituent of the active site, but located in a different region.
D001665:Binding Sites; D003545:Cysteine / Q000494:pharmacology*; D007532:Isoleucine / Q000494:pharmacology; D007700:Kinetics; D010944:Plants / Q000201:enzymology; D013237:Stereoisomerism; D013913:Threonine Dehydratase / Q000037:antagonists & inhibitors*
D007532:Isoleucine; D013913:Threonine Dehydratase; D003545:Cysteine