ON THE METABOLIC BREAKDOWN OF HEMOGLOBIN AND THE ELECTRONIC STRUCTURE OF THE BILE PIGMENTS.
ON THE METABOLIC BREAKDOWN OF HEMOGLOBIN AND THE ELECTRONIC STRUCTURE OF THE BILE PIGMENTS.
复制标题
关于血红蛋白的代谢分解和胆汁色素的电子结构。
DOI：
10.1073/pnas.45.10.1476
复制
发表时间：
1959
影响因子：
11.1
通讯作者：
A. Pérault
中科院分区：
文献类型：
--
作者：
B. Pullman;A. Pérault
血红蛋白的代谢分解在其第一阶段包括原卟啉环的氧化裂解，通过消除位于带有乙烯基取代基（α-次甲基）的两个吡咯环之间的次甲基。形成的产物胆红蛋白很容易分裂成球蛋白、铁离子和绿色色素胆绿素 (I)，胆绿素 (I) 是一种开链共轭四吡咯。进一步的代谢转化包括一系列还原：胆绿素通过分别将中心或两个末端次甲基基团 -CH=- 转化为亚甲基基团 -CH2-，被还原为胆红素 (II)（一种橙色色素），也可能还原为深棕色色素，称为尿胆素 (III)。进一步的还原导致所有次甲基和乙烯基氢化成尿胆素原，并通过两个末端吡咯环的互补部分氢化成粪胆素。胆绿素和胆红素是主要的胆汁。具有键合最低空分子轨道的不寻常特性似乎取决于聚吡咯链中吡咯环的数量：它不存在于二吡咯链中，但在四吡咯链中表现出来。 （在胆绿素的未取代的四吡咯类似物中，该轨道的键合特征应该比胆绿素本身更明显：其K = 0.064。）目前，我们正在研究出现这种不寻常性质所需的一般条件。
The metabolic breakdown of hemoglobin consists, in its first phase, in an oxidative cleavage of the protoporphyrin ring, through the elimination of the methine group situated between the two pyrrole rings carrying the vinyl substituents (a-methine group). The product formed, choleglobin, is then easily split into globin, ferric ions and a green pigment, biliverdin (I) which is an open chain conjugated totrapyrrole. The further metabolic transformations consist in a chain of reductions: biliverdin is reduced to bilirubin (II), a pigment of orange color and possibly also to a dark brown pigment, called urobilin (III), through the conversion of, respectively, the central or the two terminal methine groups, -CH=-, to methylene groups -CH2-. Further reductions lead through the hydrogenation of all the methine and the vinyl groups to urobilinogen, and through the complementary partial hydrogenation of the two terminal pyrrole rings to stercobilin. Biliverdin and bilirubin are the principal bile The unusual property of possessing a bonding lowest empty molecular orbital appears to be de-pendent on the number of pyrrole rings in the polypyrrole chain: it is not present in the dipyr- role chain but manifests itself in the tetrapyrrole chain. (In the unsubstituted tetrapyrrole analog of biliverdin the bonding character of this orbital should be even more pronounced than in biliverdin itself: its K, = 0.064.) We are investigating, at present, the general conditions necessary for the appearance of this unusual property.