Bile pigment, formation

The metabolism of naturally occurring tetrapyrrole metal complexes includes irreversible oxygenation and hydrogenation reactions (bile pigment formation, protochlorophyll hydrogenation). 

Lemberg, R. and Legge, J.W. (1949) Chemical mechanism of bile pigment formation and other irreversible alterations of hemoglobin. In Hematin Compounds and Bile Pigments. Interscience, New York, pp. 475 82. 

On the basis of bile pigment formation from aged erythrocytes labeled with N -glycine, one would expect labeled bile pigments to appear only about 120 days after the initial labeling. However, London and co-workers have found that labeled stercobilin appears in the feces within... 

The series of reactions which bring about these changes in the cells are not known precisely. However, the studies of Lemberg, of Libowitzky and Fischer,of Siedel, Watson, and others have indicated the possible chemical pathway for bile pigment formation from heme. The process appears to be an oxidative one in which the heme apparently catalyzes its own destruction (Fig. 20). 

On the basis of bile pigment formation from aged erythrocytes labeled... 

H. Bile Pigment Formation and Heme-Catalyzed Oxidations. 195... 

To quantitate and analyze conjugated bile pigments, azo derivative formation is applied most frequently (Fig. 1). Such terms as azobilirubin, or azobilirubin conjugate, erroneously suggest tetrapyrrolic structures. The following trivial names appear to be more appropriate dipyrromethene azo derivative, azodipyrrole, dipyrrolic azo pigment, and the like. The term azodipyrrole will be employed in the present review. 

Brown SB (1976) A model for the formation of bile-pigments isomers in vivo and in vitro. Biochem J 159 23-27... 

Biochemically, a change in structure relating to the mucopolysaccharides (neuraminic add ) and monohydroxy bile acids probably accounts for the formation of biliary thrombi. Some of the under-hydroxylated bile salts appear in crystalline form the bile becomes increasingly viscous and its flow is impeded. This defect in the excretion of bile salts culminates in dysfunctions in the secretion of bilirubin, which is why bilirubin is regurgitated into the blood. The bile which accmnulates in the bile ducts ultimately becomes mucous and white because of the reabsorption of bile pigments by the epitheha of the small bile ducts. 

The main cause of cholelithiasis (presence or formation of gallstones) is precipitation of cholesterol in bile. Elevated biliary concentrations of bile pigments (bilirubin... 

Each day hepatocytes secrete about 1L of bile, consisting mostly of water, ions, bile salts (important for the absorption of lipids), cholesterol, and bile pigments. Bile formation by hepatocytes requires the active secretion of inorganic and organic solutes into the canalicular lumen, followed by the movement of water. Other solutes can be carried with this movement of water through the tight junctions between hepatocytes. 

Sjostrand, T., The formation of carbon monoxide by in vitro decomposition of haemoglobin in bile pigments. Acta Physiol. Scand. 27, 231 (1952). 

Troxler, R. F., and J. M. Dokos (1973). Formation of carbon monoxide and bile pigment in red and green algae. Plant Physiol. 51, 72-75. 

In our earlier article we reviewed the main methods then available for the synthesis of naturally occurring porphyrins and bile pigments, and the structurally and biosynthetically related vitamin (cobalamin). The review essentially covered material published up to the middle of 1971. In the present article we describe new developments during the subsequent nine years. In order to preserve continuity with the earlier article and for ease of cross-referencing we have used a similar format and order of topics. 

Isomerically pure biliverdin can be prepared from pure bilirubin IXa by oxidation with chloranil acidic reagents cause some isomerization with formation of the III and XllI isomers. A variety of synthetic and spectroscopic studies have been carried out by the Vienna group on model systems" related to the reduced bile pigments, in connection with studies of the conformation and... 

Formation of bile pigments requires oxidative ring-opening... 

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