血红素调节中的色氨酸吡咯酶。色氨酸对大鼠肝脏5-氨基酮戊酸合酶活性及色氨酸吡咯酶血红素饱和度的相反作用机制。

Administration of tryptophan to starved rats causes a rapid decrease in liver 5-aminolaevulinate synthase activity associated with an increase in the haem saturation of tryptophan pyrrolase. Both effects are maximally produced at 30 min by a 100 mg/kg body wt. dose of tryptophan. 2. Pb2+ prevents both effects. 3. Prevention by allopurinol or benserazide of the tryptophan-induced increase in the haem saturation of tryptophan pyrrolase renders this haem available for further repression of synthase synthesis. 4. The opposite effects on synthase activity and pyrrolase saturation with haem caused by administration of 5-aminolaevulinate, but not those by that of haematin, are potentiated by tryptophan. 5. It is suggested that tryptophan decreases 5-aminolaevulinate synthase activity and causes the initial increase in the haem saturation of tryptophan pyrrolase by enhancing the conversion of 5-aminolaevulinate into haem by a process requiring protein synthesis.

给饥饿的大鼠注射色氨酸会导致肝脏5-氨基酮戊酸合酶活性迅速下降，同时色氨酸吡咯酶的血红素饱和度增加。这两种效应在注射100mg/kg体重剂量的色氨酸30分钟时达到最大。2. Pb2+可阻止这两种效应。3. 别嘌呤醇或苄丝肼对色氨酸诱导的色氨酸吡咯酶血红素饱和度增加的预防作用，使这种血红素可用于进一步抑制合酶的合成。4. 注射5-氨基酮戊酸对合酶活性和吡咯酶血红素饱和度产生的相反作用（而不是血红素产生的作用），会因色氨酸而增强。5. 有人提出，色氨酸通过一个需要蛋白质合成的过程增强5-氨基酮戊酸向血红素的转化，从而降低5-氨基酮戊酸合酶活性，并导致色氨酸吡咯酶血红素饱和度最初的增加。

Tryptophan pyrrolase in haem regulation. The mechanism of the opposite effects of tryptophan on rat liver 5-aminolaevulinate synthase activity and the haem saturation of tryptophan pyrrolase.