N-delta-acetylornithine and S-methylcysteine in blood plasma.

N-delta-Acetylornithine and S-methylcysteine have been identified as minor components of deproteinized blood plasma of human and bovine blood. Human blood plasma contains a variable amount of acetylornithine, averaging 1.1 +/- 0.4 mumol/l (range 0.8--0.2 mumol/l). Urine contains a very small amount of acetylornithine, approximately 1 nmol/mg creatinine (1 mumol/day). Human blood plasma contains 3.9 +/- 1.9 mumol/l (range 1.4--6.5 mumol/l) of S-methylcysteine. Urine contains approximately 5 nmol/mg creatinine; after acid hydrolysis the amount is increased to 20 nmol/mg creatinine.