Amino acid metabolism proline

All amino acids, except proline, may be used by Saccharomyces cerevisiae in grape juice fermentation. Amino acids can be directly used to synthesize proteins. However, the amino acid composition of the grape juice is not necessarily similar to the needs of the cell. For that reason, yeasts must use the remaining amino acids to synthesize those which it lacks (Hensche and Jiranek 1993 Ribereau-Gayon et al. 2000b). In this case, ammonia is incorporated into other amino acids whereas the carbon skeleton is metabolized by the cell. 

A few other less studied biochemical approaches such as purine and pyrimidine metabolism protein biosynthesis and lipid metabohsm in helminths also provide targets for antiparasitic drug design [83]. Like protozoal parasites, some helminths such as S. mansoni (adult and larval forms) lack de novo purine biosynthesis and, therefore, depend entirely on the salvage mechanism for their purine requirements. Similarly amino acid metabolism and biosynthesis of proteins has also been not worked out in many parasites [83a]. Although the helminths meet their requirements of amino acids by absorbing freely from the host, they may also synthesize some amino acids. For example. Fasciola hepatica, schistosomes and other trematodes produce proline by a reaction sequence given in Chart 8. Similarly H. diminuta can... 

Glutamate is a central amino acid in general amino-acid metabolism. It plays a major role in transamination, ammonia production, formation of ornithine, proline, glutamine, and g-amino butyric acid (GABA). 

With respect to amino acid metabolism some of the differences between host and parasite are somewhat subtle. Some parasite enzymes, for example, have properties which are clearly distinct from those of their mammalian counterparts, such as the cofactor dependence and regulation of glutamate dehydrogenases. The utilization of specific amino acids such as proline or the accumulation of others such as alanine reflects a difference in the relative importance of the pathways between parasite and host. Some differences are particularly striking, especially among anaerobic protozoa in... 

In studies on the role of the adrenal hormones in amino acid metabolism, cortisone has been reported to inhibit the incorporation of glycine and alanine into liver proteins and to increase the catabolism of glycine (Clark, 1950 Sinex, 1951 Barton, 1951). Proline oxidation by kidney homogenates was depressed by adrenalectomy and restored to normal by cortisone (Umbreit and Tonhazy, 1951a, 1951b). 

FIGURE 11.9 A Non-protein amino acid that interferes with proline metabolism. 

Figure 9-3. Fates of the carbon skeletons upon metabolism of the amino acids. Points of entry at various steps of the tricarboxylic acid (TCA) cycle, glycolysis and gluconeogenesis are shown for the carbons skeletons of the amino acids. Note the multiple fates of the glucogenic amino acids glycine (Gly), serine (Ser), and threonine (Thr) as well as the combined glucogenic and ketogenic amino acids phenylalanine (Phe), tryptophan (Trp), and tyrosine (Tyr). Ala, alanine Cys, cysteine lie, isoleucine Leu, leucine Lys, lysine Asn, asparagine Asp, aspartate Arg, arginine His, histidine Glu, glutamate Gin, glutamine Pro, proline Val, valine Met, methionine.

Corticotropin (adrenocorticotropic hormone, ACTH) regulates the function of the adrenal cortex and has numerous other effects on metabolism. It contains 39 amino acids in the form of a random coil, owing to the presence of several proline residues that prevent helix formation. Species differences are seen in amino acids 25-39 the rest of the ACTH molecule is identical in all animals and humans. The first 24 amino acids are responsible for all of the biological action of ACTH synthetic human ACTHj 24 is known as cosyntropin. 

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