Val-Tyr-Pro-Asp-Ser-Ala

Fig. 6.28. Breakdown reactions of Val-Tyr-Xaa3-Asp-Xaa5-Ala as a function of pH (Asu = aspartic succinimide) [93] [96], a) Breakdown reactions of Val-Tyr-Pro-Asp-Gly-Ala in pH ranges 1-3, 4-5, and 6-10. b) Breakdown reactions of Val-Tyr-Pro-Asp-Ser-Ala, Val-Tyr-Pro-Asp-Val-Ala, and Val-Tyr-Gly-Asp-Gly-Ala at pH 1. c) Breakdown reactions of the same...

At pH 10 and 70°, the hexapeptides had tm values for degradation of ca. 30-40 h, with the exception of Val-Tyr-Pro-Asp-Val-Ala, the stability of which was much greater (t1/2 ca. 800 h). Here, the hexapeptides containing Asp-Gly or Asp-Ser were clearly much more reactive than the Asp-Val hexapeptide. Interestingly, the D,L-iso-aspartic hexapeptide was the only product formed from the Asp-Gly hexapeptides, and it was the major product from the Asp-Ser hexapeptide (Fig. 6.28,a and c). Formation of the D-Asp hexapeptide was observed for the Asp-Ser hexapeptide, and it was the major one for the Asp-Val hexapeptide, presumably because base-catalyzed epimerization had ample time to occur given the very slow rate of other breakdown reaction. 

The complete answer is read directly, starting at Ser-Tyr- (just above), overlapping Val-Tyr with the large trypsin piece, and then on to the end Ser-Tyr-Ser-Mot-Gln-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-Lys-I.ys-Arg-Arg-Pro-Val-Lys-Val-Tyr-Pro-Asp-Ala-Gly-Giu-Asp-GIn-.Scr-Ala-Glu-Ala-Phe-Pro-Leu-Glu-Phc... 

Corticotropin, adrenocorticotropln, adrenocorticotropic hormone, ACTH a polypeptide hormone secreted by the pituitary. The primary structure of the human hormone is Ser-T -Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Tyr-Pro-Asn-Gly-Ala-Glu-Asp-Glu-Leu-Glu-Phe, M, 4541. Only sequence 31-33 is species-specific. Biological activity is determined by the first (hxed) 20 amino acids. Sequence 1-13 is identical to that of a-melanotropin. 

Secreted by the pituitary gland, corticotropin is a hormone that stimulates the adrenal cortex. Determine its primary structure fiom the following information, (i) Hydrolysis by chymotrypsin produces six peptides Arg-Trp, Ser-Tyr, Pro-Leu-Glu-Phe, Ser-Met-Glu-His-Phe, Pro-Asp-Ala-Gly-Glu-Asp-Gln-Ser-Ala-Glu-Ala-Phe, and Gly-Lys-Pro-Val-Gly-Lys-Lys-Arg-Arg-Pro-Val-Lys-Val-Tyr. (ii) Hydrolysis by trypsin produces free lysine, free arginine, and the following five peptides Trp-Gly-Lys, Pro-Val-Lys, Pro-Val-Gly-Lys, Ser-Tyr-Ser-Met-Glu-His-Phe-Arg, and Val-Tyr-Pro-Asp-Ala-Gly-Glu-Asp-Gln-Ser-Ala-Glu-Ala-Phe-Pro-Leu-Glu-Phe. 

Microwave synthesis of the 30mer peptide Val-Tyr-Trp-Thr-Ser-Pro-Phe-Met-Lys-Leu-Ile-His-Glu-Gln-Cys-Asn-Arg-Ala-Asp-Gly-Val-Gln-Ala-Ala-Ile-Asp-Tyr-Ile-Asn-Gly with crude purity of 80.0% has also been reported. 

Amino acids Cheese contains at least 20 amino acids. In the cheese made from pasteurized milk as the ripening age increases the concentration of the amino acids also increases. The most commonly identified amino acids in cheeses are as follows Asp, Glu,Asn, Thr,Val, Phe, Lys, Gly, Ala, Met, Leu, His, Tyr, Pro, He, Ser, Gin, Tau (Taurine), GABA (Gama Amino butyric acis), Arg, Cys, Trp, Orn (Ornithine) [86]. 

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