兔子体内的色氨酸代谢

Tryptophan metabolism in rabbits.

作者信息

Allegri Graziella, Ragazzi Eugenio, Bertazzo Antonella, Biasiolo Monica, Costa Carlo V L

机构信息

Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, I-35131 Padova, Italy.

出版信息

Adv Exp Med Biol. 2003;527:473-9. doi: 10.1007/978-1-4615-0135-0_55.

DOI:10.1007/978-1-4615-0135-0_55

PMID:15206765

Abstract

Enzyme activities involved in tryptophan metabolism along the kynurenine pathway were studied in male New Zealand white rabbits. Activities are expressed both as specific activity and per g of fresh tissue. Liver tryptophan 2,3-dioxygenase activity (TDO), when assayed in either the absence (holoenzyme) or presence of added haematin (apoenzyme), did not change. Therefore, in rabbit, TDO was present only in holoenzyme form. Small intestine indole 2,3-dioxygenase was significantly higher than liver TDO. Mitochondrial kynurenine 3-monooxygenase was higher in liver than in kidney. Kynureninase activity was similar in both tissues, whereas kynurenine-oxoglutarate transaminase was markedly higher in kidney than in liver. 3-Hydroxyanthranilate 3,4-dioxygenase and aminocarboxymuconate-semialdehyde decarboxylase activities were higher in kidney than in liver. However, the former enzyme showed much higher activity than the latter. These findings suggest that, in rabbit, tryptophan is mainly metabolised along the kynurenine pathway although the apo-TDO enzyme is lacking, as high indole 2,3-dioxygenase activity can obviate this lack.

摘要

在雄性新西兰白兔中研究了色氨酸沿犬尿氨酸途径代谢所涉及的酶活性。活性以比活性和每克新鲜组织来表示。肝脏色氨酸2,3-双加氧酶活性（TDO），在无添加血红素（全酶）或添加血红素（脱辅基酶）的情况下进行测定时，没有变化。因此，在兔中，TDO仅以全酶形式存在。小肠吲哚2,3-双加氧酶明显高于肝脏TDO。线粒体犬尿氨酸3-单加氧酶在肝脏中高于肾脏。犬尿氨酸酶活性在两种组织中相似，而犬尿氨酸-2-氧代戊二酸转氨酶在肾脏中明显高于肝脏。3-羟基邻氨基苯甲酸3,4-双加氧酶和氨基羧基粘康酸半醛脱羧酶活性在肾脏中高于肝脏。然而，前一种酶的活性比后一种酶高得多。这些发现表明，在兔中，尽管缺乏脱辅基TDO酶，但色氨酸主要沿犬尿氨酸途径代谢，因为高吲哚2,3-双加氧酶活性可以弥补这种缺乏。