Metabolism of 3-methylhistidine in man.
The metabolism of L-3-methylhistidine was studied in man using intravenously administered ((14)C)3-methylhistidine. Analysis for expired (14)CO2 for periods up to 2 hr following a single intravenous injection revealed no radioactivity, indicating that this compound is not oxidized in man. Analysis of urine samples for total radioactivity showed that 75% of the administered dose was excreted in 24 hr and 95% in 48 hr. Ion-exchange chromatography of urine samples with monitoring of the column eluated by a flow liquid-scintillation technique showed the presence of only two radioactive peaks. The time taken to elute these peaks was compatible with the major excretory component (95.5%) being ((14)C)3-methylhistidine, accompanied by a small amount (4.5%) in the form of N-acetyl-((14)C)3-methylhistidine. The plasma disappearance curves of ((14)C)3-methylhistidine suggested a half-life of approximately 130 min. The inability ot oxidize 3-methylhistidine and its quantitative excretion as the original compound as well as its N-acetyl derivative is similar to its metabolic fate in the rat and therefore suggests that 3-methylhistidine excretion may provide a reliable measure of actin and myosin turnover in the whole animal or in human subjects.
D000107:Acetylation; D000328:Adult; D000367:Age Factors; D000596:Amino Acids / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D005260:Female; D006639:Histidine / Q000031:analogs & derivatives*; D006801:Humans; D008297:Male; D008762:Methylhistidines / Q000097:blood / Q000378:metabolism* / Q000652:urine; D008875:Middle Aged; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D011506:Proteins / Q000378:metabolism; D012737:Sex Factors; D013045:Species Specificity
D000596:Amino Acids; D002250:Carbon Radioisotopes; D008762:Methylhistidines; D011506:Proteins; D002245:Carbon Dioxide; D006639:Histidine