Treponema denticola cystalysin catalyzes beta-desulfination of L-cysteine sulfinic acid and beta-decarboxylation of L-aspartate and oxalacetate.
Pyridoxal 5'-phosphate-dependent cystalysin from Treponema denticola catalyzes the beta-displacement of the beta-substituent from both L-aspartate and L-cysteine sulfinic acid. The steady-state kinetic parameters for beta-desulfination of L-cysteine sulfinic acid, k(cat) and K(m), are 89+/-7 s(-1) and 49+/-9 mM, respectively, whereas those for beta-decarboxylation of L-aspartate are 0.8+/-0.1 s(-1) and 280+/-70 mM. Moreover, cystalysin in the pyridoxamine 5'-phosphate form has also been found to catalyze beta-decarboxylation of oxalacetate as shown by consumption of oxalacetate and a concomitant production of pyruvate. The k(cat) and K(m) of this reaction are 0.15+/-0.01 s(-1) and 13+/-2 mM, respectively. Possible mechanistic and physiological implications are discussed.
Cellini
Barbara
B
Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Verona, Strada Le Grazie, 8, 37134 Verona, Italy. carla.borrivoltattorni@univr.it
Bertoldi
Mariarita
M
Borri Voltattorni
Carla
C
D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism; D002384:Catalysis; D002417:Cattle; D003542:Cystathionine gamma-Lyase / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D003653:Decarboxylation; D007700:Kinetics; D018377:Neurotransmitter Agents; D010071:Oxaloacetates / Q000737:chemistry / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D011817:Rabbits; D013053:Spectrophotometry / Q000379:methods; D014208:Treponema / Q000201:enzymology*
D018377:Neurotransmitter Agents; D010071:Oxaloacetates; D001224:Aspartic Acid; D011732:Pyridoxal Phosphate; D019289:Pyruvic Acid; D002262:Carboxy-Lyases; C400145:cystalysin; D003542:Cystathionine gamma-Lyase; D003545:Cysteine; C013461:cysteine sulfinic acid