Heacock A M, Adams E
J Biol Chem. 1975 Apr 10;250(7):2599-608.
A corrected method for the measurement of pyrrole-2-carboxylate in rat urine was used in studies of its excretion under various experimental conditions. The findings implicated administered hydroxy-L-proline as a relatively efficient source of urinary pyrrole-2-carboxylate and tended to exclude administered L-proline as a significant direct source. Removal of aerobic gut flora had no influence on the excretion of pyrrole-2-carboxylate either endogenously or following hydroxy-L-proline administration. Related studied showed that rat kidney L-amino acid oxidase catalyzes oxidation of hydroxy-L-proline to delta1-pyrroline-4-hydroxy-2-carboxylate, which is converted to pyrrole-2-carboxylate on acidification of reaction mixtures. All findings were consistent with hydroxy-L-proline as the source of endogenous pyrrole-2-carboxylate excretion. Excretion patterns and labeling patterns were compared after administration of pyrrole-2-carboxylate or of hydroxy-proline epimers. From these data, the true excretion product of hydroxy-L-proline oxidation by L-amino acid oxidase appeared to be the unstable oxidation product, delta1-pyrroline-4-hydroxy-2-carboxylate, which is converted to pyrrole-2-carboxylate in urine. The capacity of homogenates of guinea pig kidney and human kidney to carry out oxidation of hydroxy-L-proline to pyrrole-2-carboxylate was much less than that of rat kidney, consistent with the lower levels of urinary pyrrole-2-carboxylate in these species. Experiments designed to examine the modest increase of pyrrole-2-carboxylate excretion after proline loads led to new observations on tissue levels of hydroxy-L-proline following proline administration and on the inhibition by L-proline of hydroxy-L-proline oxidase.
一种校正的大鼠尿液中吡咯 - 2 - 羧酸盐测量方法被用于研究其在各种实验条件下的排泄情况。研究结果表明，给予的羟基 - L - 脯氨酸是尿液中吡咯 - 2 - 羧酸盐相对有效的来源，而给予的L - 脯氨酸似乎不是重要的直接来源。去除需氧肠道菌群对内源性或给予羟基 - L - 脯氨酸后吡咯 - 2 - 羧酸盐的排泄没有影响。相关研究表明，大鼠肾脏L - 氨基酸氧化酶催化羟基 - L - 脯氨酸氧化为δ1 - 吡咯啉 - 4 - 羟基 - 2 - 羧酸盐，在反应混合物酸化时该物质会转化为吡咯 - 2 - 羧酸盐。所有研究结果都与羟基 - L - 脯氨酸作为内源性吡咯 - 2 - 羧酸盐排泄来源一致。在给予吡咯 - 2 - 羧酸盐或羟基 - 脯氨酸差向异构体后，比较了排泄模式和标记模式。根据这些数据，L - 氨基酸氧化酶氧化羟基 - L - 脯氨酸的真正排泄产物似乎是不稳定的氧化产物δ1 - 吡咯啉 - 4 - 羟基 - 2 - 羧酸盐，它在尿液中会转化为吡咯 - 2 - 羧酸盐。豚鼠肾脏和人肾脏匀浆将羟基 - L - 脯氨酸氧化为吡咯 - 2 - 羧酸盐的能力远低于大鼠肾脏，这与这些物种尿液中吡咯 - 2 - 羧酸盐水平较低一致。旨在研究脯氨酸负荷后吡咯 - 2 - 羧酸盐排泄适度增加的实验，带来了关于脯氨酸给药后组织中羟基 - L - 脯氨酸水平以及L - 脯氨酸对羟基 - L - 脯氨酸氧化酶抑制作用的新观察结果。
