In vitro oxidative decarboxylation of L-2-hydroxy-4-methylthiobutanoic acid by L-2-hydroxy acid oxidase A from chicken liver.
The first step in the set of reactions responsible for the biological utilization of L-2-hydroxy-4-methylthiobutanoic acid, the methionine hydroxy analogue, in protein synthesis was investigated in vitro using pure L-2-hydroxy acid oxidase A from chicken liver. The reaction yielded no more than 20% of the corresponding alpha-keto acid, the well-known intermediate in methionine metabolism, and as much as 80% of the subsequent decarboxylation product, 3-methylthiopropionate, suggesting that L-2-hydroxy-4-methylthiobutanoic acid cannot be completely converted into methionine in vivo. It was therefore concluded that chicken liver L-2-hydroxy acid oxidase, a peroxisomal enzyme requiring flavin mononucleotide as a coenzyme, also has an oxidative decarboxylation activity in vitro, which was found to be NADH-dependent. The mechanism possibly underlying the successive conversion of the methionine hydroxy analogue into alpha-keto acid and 3-methylthiopropionate by this NADH:flavin oxidoreductase-decarboxylase activity is described.
Ferjancic-Biagini
A
A
Laboratoire de Biochimie et Biologie de la Nutrition, CNRS-URA 1820, Faculté des Sciences et Techniques Saint-Jérôme, Marseille, France.
Dupuis
L
L
De Caro
J
J
Puigserver
A
A
D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002645:Chickens; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003653:Decarboxylation; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008715:Methionine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared
D011422:Propionates; C008391:alpha-hydroxy-gamma-methylmercaptobutyric acid; C014632:2-keto-4-methylthiobutyric acid; C017526:3-methylthiopropionate; D008715:Methionine; D000429:Alcohol Oxidoreductases