Refsum H, Helland S, Ueland P M
Clin Chem. 1985 Apr;31(4):624-8.
Using a modification of the radioenzymic assay described previously (J Biol Chem 259: 2360-2364, 1984) we measured homocysteine in freshly prepared plasma and urine from volunteers. The concentration of free homocysteine--i.e., the amount measurable in plasma after deproteinization by strong acid--was 2.27 (SEM 0.11) mumol/L for 18 men and 1.95 (SEM 0.13) mumol/L for 16 women (p greater than 0.05, not significant). About 70% of the total homocysteine in human plasma was associated with plasma proteins, and was precipitated with strong acid. The concentration of protein-bound homocysteine in plasma was 6.51 (SEM 0.32) mumol/L for men and 7.29 (SEM 0.65) mumol/L for women, a significantly (p less than 0.01) different spread. Homocysteine was rapidly released from plasma proteins in the presence of a reducing agent, dithioerythritol. By gel filtration of plasma on a "high-performance" liquid-chromatographic column, albumin was shown to be the sole carrier of homocysteine in plasma. Because the fraction bound to protein as determined by this procedure equaled that obtained by precipitation of plasma proteins with acid, we conclude that homocysteine is bound to albumin in vivo. The concentration of homocysteine in urine ranged from 3.5 to 9.5 mumol/L, about 6 mumol of homocysteine being excreted per 24 h.
我们采用之前描述的放射性酶测定法的一种改良方法（《生物化学杂志》259: 2360 - 2364, 1984），对志愿者新鲜制备的血浆和尿液中的同型半胱氨酸进行了测量。游离同型半胱氨酸的浓度，即强酸脱蛋白后血浆中可测量的量，18名男性为2.27（标准误0.11）μmol/L，16名女性为1.95（标准误0.13）μmol/L（p>0.05，无显著差异）。人血浆中约70%的总同型半胱氨酸与血浆蛋白结合，并可被强酸沉淀。血浆中与蛋白结合的同型半胱氨酸浓度，男性为6.51（标准误0.32）μmol/L，女性为7.29（标准误0.65）μmol/L，差异有统计学意义（p<0.01）。在还原剂二硫苏糖醇存在的情况下，同型半胱氨酸会迅速从血浆蛋白中释放出来。通过在“高效”液相色谱柱上对血浆进行凝胶过滤，发现白蛋白是血浆中同型半胱氨酸的唯一载体。由于通过该方法测定的与蛋白结合的部分与用酸沉淀血浆蛋白得到的部分相等，我们得出结论，同型半胱氨酸在体内与白蛋白结合。尿液中同型半胱氨酸的浓度范围为3.5至9.5μmol/L，每24小时约有6μmol的同型半胱氨酸排出。
