Topic
Tryptophan
About: Tryptophan is a research topic. Over the lifetime, 11677 publications have been published within this topic receiving 351150 citations. The topic is also known as: L-Trp & (-)-Tryptophan.
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TL;DR: A procedure is presented which strongly reduces or elimi- nates these interactions, normalizes their absorption, and consequently permits a more precise analysis of tryptophan and tyrosine in proteins.
Abstract: A rapid method for the determination of tryptophan in proteins is presented. It is based on ab- sorbance measurements at 288 and 280 mp of the protein dissolved in 6 M guanidine hydrochloride. Blocked tryptophanyl (N-acetyl-L-tryptophanamide) and tyrosyl (glycyl-L-tyrosylglycine) compounds were selected as C urrent methods of protein amino acid analysis do not give quantitative values for tryptophan and conse- quently the amino acid compositions, which are other- wise complete, fail to report tryptophan values. The principal reason for this situation is that the standard procedure of protein hydrolysis in strong acid results in the destruction of tryptophan (Hill, 1965). Therefore a second procedure is required to measure tryptophan. Alkaline hydrolysis is less destructive but does not give quantitative recoveries generally (Spies and Chambers, 1949). Enzymatic hydrolysis of proteins can give quanti- tative yields of tryptophan but this method may not be generally valid (Hill and Schmidt, 1962). The hydrolytic problem can be circumvented by meas- uring tryptophan in the intact protein. A chemical method has been developed which has not been exploited adequately (Spies and Chambers, 1948, 1949). On the other hand, considerable effort has been expended in developing absorption spectroscopic procedures to measure tryptophan and tyrosine in unhydrolyzed pro- teins. Holiday (1936) and Goodwin and Morton (1946) have measured the absorption of proteins in 0.1 M NaOH and computed their tryptophan and tyrosine contents based on comparison with the absorption of the two amino acids. A modification of these techniques has been presented by Bencze and Schmid (1957). The pre- ceding three methods do not give quantitative results. The behavior of the chromophores has not been nor- malized and the two models, i.e., tryptophan and tyro- sine, are not completely adequate. A procedure is sug- gested in this report which strongly reduces or elimi- nates these interactions, normalizes their absorption, and consequently permits a more precise analysis of tryptophan and tyrosine in proteins.
3,323 citations
TL;DR: The results indicate a general sensitivity of proteins to oxygen radicals and indicate that proteins which have been denatured by .OH can be recognized and degraded rapidly and selectively by intracellular proteolytic systems.
1,571 citations
TL;DR: (All right. re8erved)
Abstract: (All right. re8erved) PAGE Protocatechuic acid, the substance responsible for the hardening of the cockroach ootheca. By M. G. M. PRYOR, P. B. RUSSELL and A. R. TODD . . . . . . . . . . . . 627 The spectrophotometric determination of tyrosine and tryptophan in proteins. By T. W. GOODwn and R. A. MORTON . . . . . . . . . . . . . . . . . 628 The estimation of threonine and serine in proteins. By M. W. REES. (With two figures) . . . . 632 Tetryl dermatitis. *2. The interaction of aromatic mitro-compounds with amino-acids and proteins. By I. A. BROWNLIE and W. M. CUMMNG. (With six figures) . . . . . . . . . 640 A modification of the fluorimetric method of determining riboflavin in biological materials. By E. C. SLATER and D. B. MORELL. (With two figures) . . . . . . . . . . . . 644 The fluorimetric determination ofriboflavin in urine. By D. B. MORELL and E. C. SLATER . . . . 652 Carotenoid pigments ofBadami mango fruit. By G. B. RAMAsARMA, S. D. RAO and D. N. HAIM . . . 657 Porphyrin metabolism in yeast. By J. E. KENCH and J. F. WILKSON . . . . . . . 660 The fatty acid and glyceride structures of Indian buffalo milk and depot fats, and some characteristics of eastern animal fats. By K. T. ACHAYA and B. N. BANERJEE. (With one figure). . . . 664 Indigoid pigments derived from a pathological urine. By C. RMINGTTON. With an addendum on 'The spectral absorption of the pigments' by E. R. HOLIDAY and E. M. JOPE. (With six figures) . . . . 669 Combination between different protpins and between proteins and yeast nucleic acid. By A. KLECZKOWSKI. (With one figure) . . . . . . . . . . . . . . . . . 677 The determination and isolation of the organic acids in fruit. By F. A. ISHERWOOD. (With four figures) . 688 The fixation and retention of ascorbic acid by the guinea-pig. By J. R. PENNEY and S. S. ZILVA. (With four figures) . . . . . . . . . . . . . . . . . . 695 Spectrophotometric study of the excretion products of mepacrine compared with synthetic acridine and diph.enylamine derivatives. By E. J. KING, M. GILCHST and A. L. TURNOKY. (With five figures) . 706 Observations upon the application of partition chromatography to the determinationof the monoamino-acids in proteins. By G. R. TRISTRAM. (With three diagrams) . . . . . . . . . 721 Studies on mustard gas(,Bp'-dichlorodiethyl sulphide) and some related compounds. 1. General introduction and acknowledgements. By T. E. BANKS, J. C. BOUrRSNELL, G. E. FRANCIS, F. L. HoPwoOD and A. WORMALL . . . . . . . . . . . . . . . . . 734
1,403 citations
TL;DR: A short and simple calorimetric method is here described that is applicable to the determination of hydroxyproline in hydrolysates of 40 to 100 y of collagen with a reproducibility of f2 per cent and an accuracy of f1 per cent as judged by recovery of hydroXYproline from elastin hydrolysate and from an amino acid mixture simulating collagen.
1,249 citations
TL;DR: The main determinant of brain tryPTophan and serotonin concentrations does not appear to be plasma tryptophan alone, but the ratio of this amino acid to other plasma neutral amino acids that compete with it for uptake into the brain.
Abstract: When plasma tryptophan is elevated by the injection of tryptophan or insulin, or by the consumption of carbohydrates, brain tryptophan and serotonin also rise; however, when even larger elevations of plasma tryptophan are produced by the ingestion of protein-containing diets, brain tryptophan and serotonin do not change. The main determinant of brain tryptophan and serotonin concentrations does not appear to be plasma tryptophan alone, but the ratio of this amino acid to other plasma neutral amino acids (that is, tyrosine, phenylalanine, leucine, isoleucine, and valine) that compete with it for uptake into the brain.
1,090 citations