title: The carboxyltransferase activity of the sodium-ion-translocating methylmalonyl-CoA decarboxylase of Veillonella alcalescens.
abstract: Methylmalonyl-CoA decarboxylase of Veillonella alcalescens catalyzed the isotopic exchange between methylmalonyl-CoA and [1-14C]propionyl-CoA or between malonyl-CoA and [1-14C]acetyl-CoA. The exchange was independent of sodium ions and was abolished by avidin. The enzyme also catalyzed the carboxyl transfer reaction from methylmalonyl-CoA to acetyl-CoA yielding propionyl-CoA and malonyl-CoA, and vice versa. The beta subunit was dissociated from methylmalonyl-CoA decarboxylase by prolonged washing of the enzyme while bound via its biotin prosthetic group to monomeric avidin-Sepharose. The beta-chain-depleted enzyme was inactive as a methylmalonyl-CoA decarboxylase but retained carboxyltransferase activity. The beta subunits were specifically protected by Na+ ions from tryptic hydrolysis. Based on these and other observations the following functions may be assigned to the different polypeptide chains of methylmalonyl-CoA decarboxylase: carboxyltransferase (alpha), carboxybiotin-carrier-protein decarboxylase (beta), biotin carrier protein (gamma). The function of the delta chain is unknown.
authors.affiliation: Institut für Physiologische Chemie, Technischen Universität München, Federal Republic of Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hoffmann
authors.forename: W
authors.initials: W
authors.lastname: Hilpert
authors.forename: P
authors.initials: P
authors.lastname: Dimroth
mesh_terms: D001692:Biological Transport; D002262:Carboxy-Lyases / Q000378:metabolism*; D019878:Carboxyl and Carbamoyl Transferases; D002851:Chromatography, High Pressure Liquid; D004800:Enzymes, Immobilized; D007700:Kinetics; D043586:Methylmalonyl-CoA Decarboxylase; D012964:Sodium / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism*; D014357:Trypsin; D014678:Veillonella / Q000201:enzymology*
chemical_list: D004800:Enzymes, Immobilized; D012964:Sodium; D014166:Transferases; D019878:Carboxyl and Carbamoyl Transferases; C021580:Methylmalonyl-CoA carboxytransferase; D014357:Trypsin; D002262:Carboxy-Lyases; D043586:Methylmalonyl-CoA Decarboxylase