Digestion acid degradation

Nagase M. and Matsuo T. (1982) Interaction between amino-acid degrading bacteria and methanogenic bacteria in anaerobic digestion. Biotechnol. Bioeng. 24, 2227-2239. 

For the majority of obese humans, who produce leptin, perhaps a genetic defect exists in the leptin receptor. Or perhaps the genetics of obesity in humans is more complex than in mice. Clearly lipid metabolism in animals is a complex process and is not yet fully understood. The discovery of the leptin gene, and the hormone it produces, is just one part of the story. In this chapter we will study other aspects of Upid metaboUsm the pathways for fatty acid degradation and biosynthesis and the processes by which dietary lipids are digested and excess Upids are stored. 

TABLE k. Molar ratios of the hydrolysis products of methylated original, acid degraded, and a-mannanase digested proteoheteroglycan from P. oryzae. 

NPCM digestion (acid, alkaline and combination treatment) Cupriavidus necator HI 6 Acid sulfuric acid -t bleaching steps Alkaline NaClO, NaOH, NaOH -t halogenated solvent Purity 98% lowest polymer degradation for acid treatment [30]... 

Oxidative degradation of [B qH q] and [B22H22] C to boric acid is extremely difficult and requires Kjeldahl digestion or neutral permanganate. The heat of reaction obtained from the permanganate degradation leads to a calculated heat of formation for [B qH q] (aq) of 92.5 21.1 kJ/mol (22.1 5.0 kcal/mol) (99). The oxidative coupling of both [B qH q] and has been studied ia some detail (100). 

The two intermediates of commercial furan resins are furfural and furfuryl alcohol. Furfural occurs in the free state in many plants but is obtained commercially by degradation of hemicellulose constituents present in these plants. There are a number of cheap sources of furfural, and theoretical yields of over 20% (on a dry basis) may be obtained from both com cobs and oat husks. In practice yields of slightly more than half these theoretical figures may be obtained. In the USA furfural is produced in large quantities by digestion of com cobs with steam and sulphuric acid. The furfural is removed by steam distillation. 

Mammals, fungi, and higher plants produce a family of proteolytic enzymes known as aspartic proteases. These enzymes are active at acidic (or sometimes neutral) pH, and each possesses two aspartic acid residues at the active site. Aspartic proteases carry out a variety of functions (Table 16.3), including digestion pepsin and ehymosin), lysosomal protein degradation eathepsin D and E), and regulation of blood pressure renin is an aspartic protease involved in the production of an otensin, a hormone that stimulates smooth muscle contraction and reduces excretion of salts and fluid). The aspartic proteases display a variety of substrate specificities, but normally they are most active in the cleavage of peptide bonds between two hydrophobic amino acid residues. The preferred substrates of pepsin, for example, contain aromatic residues on both sides of the peptide bond to be cleaved. 

While additive analysis of polyamides is usually carried out by dissolution in HFIP and hydrolysis in 6N HC1, polyphthalamides (PPAs) are quite insoluble in many solvents and very resistant to hydrolysis. The highly thermally stable PPAs can be adequately hydrolysed by means of high pressure microwave acid digestion (at 140-180 °C) in 10 mL Teflon vessels. This procedure allows simultaneous analysis of polymer composition and additives [643]. Also the polymer, oligomer and additive composition of polycarbonates can be examined after hydrolysis. However, it is necessary to optimise the reaction conditions in order to avoid degradation of bisphenol A. In the procedures for the analysis of dialkyltin stabilisers in PVC, described by Udris [644], in some instances the methods can be put on a quantitative basis, e.g. the GC determination of alcohols produced by hydrolysis of ester groups. 

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