Pectins metabolism

The hSubunit of Tomato Fruit Polygalacturonase Isoenzyme 1 Defines a New Class of Plant Cell Proteins Involved in Pectin Metabolism AroGPs (Aromatic Amino Acid Rich Glyco Proteins)... 

The effects of auxin on pectin metabolism were studied by Rubery and Northcote (1970), who employed the same sycamore cell culture line as was used by Stoddart and Northcote (1967). The techniques used in isolating and fractionating the pectin were the same as those previously used and so were known to be minimally degradative. 

Schink, B., Zeikus, J. G. Microbial methanol production. A major end product of pectin metabolism, Current Microbiol, 4, 387-389 (1980). 

This study reports on investigations of the metabolism of pectin by in vitro and in vivo experiments using chromatographic methods. 

The cultivation of this yeast strain on pectin medium showed optimal grow conditions. The behaviour of this strain was compared with that of four strains of Candida boidinii from the Culture Collection of Yeasts. The grow curves of all strains on pectin medium showed marked plateau suggesting the presence of two existing C-sources in the pectin medium, requiring two different metabolic paths (Fig. 1). 

Fernandez LM, Lin ECK, Trejo A and McNamara DJ. 1994. Prickly pear (Opuntia sp.) pectin alters hepatic cholesterol metabolism without affecting cholesterol absorption in guinea pigs fed a hypercholesterolemic diet. J Nutt 124 817-824. 

A certain amount of evidence shows that methyl group metabolism may be affected as a result of auxin treatment—generally increased pectin-methyl esterification is observed (7). Though pectin-methyl esterification may be correlated with increased wall plasticity, there are as yet no obvious connections between general methyl group availability on the one hand and permeability, peroxidation, and mitosis on the other. 

Metabolism of pectin. Pectin has only recently come, to be considered a part of the dietary fiber complex. Previously it was excluded because 1) it is not fibrous (except at the molecular level), 2) it escapes detection in standard fiber tests owing to its solubility, and 3) it usually does not survive intestinal passage. In a reassessment of which dietary components should be considered fiber, Trowell (49) proposed that dietary fiber include those constituents of food resistant to hydrolysis by man s alimentary enzymes. Spiller (50, 51) suggested that confusion surrounding the term "fiber" be avoided by using the term "plantix" to denote those plant materials of polymeric nature not attacked by human digestive enzymes. 

J. Baddiley Mechanism and control of the cell wall synthesis in bacteria J. Montreuil Recent data on the structure of the carbohydrate moiety of glycoconjugates. Metabolic and biological implications U. S. Ovodov Structural chemistry of plant glycuronoglycans R Kohn Ion binding on polyuronates—alginate and pectin... 

Although studies suggest that dietary incorporation of fermentable carbohydrates increases microfloral metabolism of xenobiotics, Rowland et al. (23) reported that dietary pectin did not uniformly increase the activity of intestinal microfloral nitroreductases that is, dietary pectin increased the cecal nitroreduction of p-nitrobenzoic acid and metronidazole, but not p-nitrophenol, 2-amino-4-nitrotoluene, or 4-amino-2-nitrotoluene. The presence of intes-... 

In vitro reductive metabolism of 14C-nitrobenzene was significantly greater in the cecal contents of rats fed NIH-07 than that in the cecal contents of either of the groups fed the AIN-76A-based diets (Table V). Furthermore, nitrobenzene metabolism by cecal contents tended to be greatest in animals fed NIH-07, least in animals fed AIN-76A, and intermediate in those fed AIN-76A containing pectin. Metabolites of nitrobenzene produced by cecal contents of animals fed NIH-07 and AIN-76A containing pectin included aniline, nitrosobenzene, and azoxybenzene, whereas aniline was the only detectable metabolite observed in animals fed the AIN-76 A diet (Table V). 

These studies indicate that intestinal microfloral metabolism and red blood cell toxicity of nitrobenzene is markedly different in animals fed cereal-based versus purified diets. Furthermore, since inclusion of pectin into the purified diet diminishes the magnitude of these effects, differences in dietary composition of fermentable carbohydrates in cereal-based and purified diets may mediate differences in metabolism and toxicity of nitrobenzene (27). 

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