Reduction of DABS-L-methionine-dl-sulfoxide by protein methionine sulfoxide reductase from polymorphonuclear leukocytes: stereospecificity towards the l-sulfoxide.
A new synthetic substrate for protein methionine sulfoxide reductase is proposed. We show that extracts from human polymorphonuclear leukocytes can reduce 4-dimethylaminoazobenzene-4'-sulfonyl-L-methionine-dl-sulfoxide [DABS-L-Met-dl-(O)] to the corresponding methionine derivative, in the presence of dithiothreitol or dithioerythritol. The product of the reaction (DABS-Met) was separated by reversed-phase HPLC and detected by reading the absorbance at 436 nm. Due to the chirality of the sulfur atom in the sulfoxide, two diastereomers of Met(O) exist, namely Met-l-sulfoxide and Met-d-sulfoxide. After separation of the two forms and preparation of the DABS-derivatives, we observed a preferential reduction of the l-sulfoxide by polymorphonuclear leukocytes extracts. We discuss the possibility that the observed stereospecificity might have physiological relevance in the field of the oxidative modifications of proteins.
Minetti
G
G
Dipartimento di Biochimica, Sezione di Scienze, Università di Pavia.
Balduini
C
C
Brovelli
A
A
D001391:Azo Compounds / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007700:Kinetics; D008715:Methionine / Q000031:analogs & derivatives* / Q000378:metabolism; D051150:Methionine Sulfoxide Reductases; D009504:Neutrophils / Q000201:enzymology*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D013454:Sulfoxides / Q000378:metabolism*
C093671:4-dimethylaminoazobenzene-4'-sulfonylmethionine sulfoxide; D001391:Azo Compounds; D013454:Sulfoxides; D008715:Methionine; D010088:Oxidoreductases; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase