Properties of 5-hydroxyvalerate CoA-transferase from Clostridium aminovalericum.
5-Hydroxyvalerate CoA-transferase from Clostridium aminovalericum, strain T2-7, was purified approximately 100-fold to homogeneity. The molecular mass of the native enzyme was determined by three different methods to be 178 +/- 11 kDa; that of the subunit was 47 kDa, indicating a homotetrameric structure. The following CoA esters acted as substrates (decreasing specificity, V/Km): 5-hydroxyvaleryl-CoA greater than propionyl-CoA greater than acetyl-CoA greater than (Z)-5-hydroxy-2-pentenoyl-CoA greater than butyryl-CoA greater than valeryl-CoA. 4-Pentenoate and 3-pentenoate were also activated by acetyl-CoA to the corresponding CoA esters, whereas crotonate, (E)-5-hydroxy-2-pentenoate, (E)-2-pentenoate and 2,4-pentadienoate were not attacked. 5-Hydroxyvalerate CoA-transferase showed ping-pong kinetics and was inactivated by sodium boranate only in the presence of a CoA substrate. This indicated the formation of a thiolester between a specific carboxyl group of the enzyme and CoASH during the course of the reaction. The CoA-transferase was inhibited by ATP and CTP, slightly by ADP, GTP and UTP, but not by AMP. The inhibition by ATP was competitive towards CoA esters and noncompetitive towards acetate.
Eikmanns
U
U
Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität Marburg.
Buckel
W
W
D003013:Clostridium / Q000187:drug effects / Q000201:enzymology*; D015256:Coenzyme A-Transferases / Q000737:chemistry / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D008970:Molecular Weight; D009711:Nucleotides / Q000494:pharmacology; D013379:Substrate Specificity
D009711:Nucleotides; C068376:5-hydroxyvalerate CoA-transferase; D015256:Coenzyme A-Transferases