Nakamura H, Kajikawa R, Ubuka T
Department of Clinical Nutrition, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan.
Amino Acids. 2002;23(4):427-31. doi: 10.1007/s00726-002-0208-9.
Sulfate and taurine are major end products of sulfur-containing amino acid metabolism in mammals including humans, and they are excreted in urine. Average excretions micromol/mg of creatinine) in the morning urine of 58 female college students were: total (free plus ester) sulfate (a). 12.53 +/- 3.85; free sulfate, 11.57 +/- 3.69; taurine, 0.78 +/- 0.53. Ratio of total sulfate and taurine was 10 : 0.6. Regression lines obtained by plotting total sulfate, free sulfate, or total sulfate plus taurine against urea have shown that the former excretions are significantly correlated with urea excretion. Excretion of total sulfate at zero point of urea excretion (b). was 5.30, which corresponded to 42.3% of average excretion (12.53) and was assumed to be derived from dietary sulfate. The difference 7.23 (a - b) seemed to be derived from sulfur-containing amino acids. It was pointed out that the difference of average sulfate excretion and sulfate excretion at zero urea excretion, namely a - b, was appropriate for the metabolic index of sulfur-containing amino acids of the group examined. As free sulfate constituted 92.3% of total sulfate, excretion of ester sulfate was at a constant level, and that of taurine was not significantly correlated with urea excretion, the value of free sulfate corresponding to the value a - b of total sulfate mentioned above seemed to be a reliable and convenient index in the assessment of sulfur-containing amino acid metabolism.
硫酸盐和牛磺酸是包括人类在内的哺乳动物含硫氨基酸代谢的主要终产物，它们通过尿液排出。58名女大学生晨尿中的平均排泄量（微摩尔/毫克肌酐）为：总（游离加酯）硫酸盐（a）12.53±3.85；游离硫酸盐11.57±3.69；牛磺酸0.78±0.53。总硫酸盐与牛磺酸的比例为10:0.6。通过将总硫酸盐、游离硫酸盐或总硫酸盐加牛磺酸与尿素作图得到的回归线表明前者的排泄量与尿素排泄量显著相关。尿素排泄量为零时的总硫酸盐排泄量（b）为5.30，相当于平均排泄量（12.53）的42.3%，假定其来自膳食硫酸盐。差值7.23（a - b）似乎来自含硫氨基酸。有人指出，平均硫酸盐排泄量与尿素排泄量为零时的硫酸盐排泄量之差，即a - b，适合作为所研究群体含硫氨基酸代谢的指标。由于游离硫酸盐占总硫酸盐的92.3%，酯硫酸盐的排泄量处于恒定水平，且牛磺酸的排泄量与尿素排泄量无显著相关性，上述总硫酸盐a - b值对应的游离硫酸盐值似乎是评估含硫氨基酸代谢的可靠且便捷的指标。
