Abnormal sulphur oxidation in systemic lupus erythematosus.
S-carboxy-L-methylcysteine was used to assess the activity of the S-oxidation pathway of sulphur metabolism in 35 patients with systemic lupus erythematosus (SLE); 25 (71%) showed impaired sulphoxidation and 21 (60%) produced virtually no sulphoxides, compared with 17 (36%) and 2 (4%), respectively, of 47 healthy controls. The substrate/product ratio of cysteine oxygenase (plasma cysteine/sulphate) was significantly higher in SLE patients than in controls (median [interquartile range] 362 [224-588] vs 65 [44-111]; p less than 0.00001). The alternative pathway of sulphur metabolism, S-methylation, catalysed by thiolmethyltransferase, was not impaired in the SLE patients. There is a biochemical difference in sulphur metabolism between SLE and rheumatoid arthritis, since both pathways are impaired in the latter disorder.
Department of Rheumatology, University of Birmingham, UK.
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Gordon
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Bradley
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Waring
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Emery
D000328:Adult; D000368:Aged; D002233:Carbocysteine / Q000378:metabolism*; D050558:Cysteine Dioxygenase; D049308:Dioxygenases; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000201:enzymology / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism*; D008875:Middle Aged; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000097:blood; D013431:Sulfates / Q000097:blood; D013455:Sulfur / Q000378:metabolism*
D013431:Sulfates; D013455:Sulfur; D002233:Carbocysteine; D010105:Oxygenases; D049308:Dioxygenases; D050558:Cysteine Dioxygenase; D008780:Methyltransferases; C022742:thiol S-methyltransferase