SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Crosses between an Escherichia coli Hfr trp strain and three Salmonella typhimurium F- trp strains produced some trp+ hybrids in which the tryptophan operon is composed of genes from both parental species.
Normal 4-day cyclic rats were sacrificed at 10 a.m. and 3 p.m. on proestrus or estrus and at 10 a.m. on metestrus. Noradrenaline (NA), dopamine (DA) and tryptophan (T) concentrations varied only slightly. Serotonin (5-HT) concentrations showed characteristic changing patterns in many hypothalamic, limbic and midbrain structures with a decrease during proestrus and an increase during estrus being observed. Monoamine oxidase (MAO) activity changes were often parallel to the 5-HT changes, but were not as great. The marked changes in 5-HT early in proestrus are a further indication of its inhibitory effect on gonadotropin release mechanisms before the 'critical period'.
The effects of amino acid composition on the conversion ratio of Trp to niacin in rats were investigated. The ratio in the group fed with a nicotinic acid-free, 9% casein-sucrose diet (basal diet) was 3.5%. This ratio was statistically decreased to 0.2% by the addition of 2% glycine, 0.078% L-threonine, and 0.2% L-cystine, and restored to 3.2% by the further addition of 0.1% tryptophan. From these results and our previous findings, it was considered that Trp imbalance might be a manifestation of niacin deficiency.
The effect of binding the Trp-free motor domain mutant of Dictyostelium discoideum, rabbit skeletal muscle myosin S1, and tropomyosin on the dynamics and conformation of actin filaments was characterized by an analysis of steady-state tryptophan phosphorescence spectra and phosphorescence decay kinetics over a temperature range of 140-293 K. The binding of the Trp-free motor domain mutant of D. discoideum to actin caused red shifts in the phosphorescence spectrum of two internal Trp residues of actin and affected the intrinsic lifetime of each emitter, decreasing by roughly twofold the short phosphorescence lifetime components (tau(1) and tau(2)) and increasing by approximately 20% the longest component (tau(3)). The alteration of actin phosphorescence by the motor protein suggests that i), structural changes occur deep down in the core of actin and that ii), subtle changes in conformation appear also on the surface but in regions distant from the motor domain binding site. When actin formed complexes with skeletal S1, an extra phosphorescence lifetime component appeared (tau(4), twice as long as tau(3)) in the phosphorescence decay that is absent in the isolated proteins. The lack of this extra component in the analogous actin-Trp-free motor domain mutant of D. discoideum complex suggests that it should be assigned to Trps in S1 that in the complex attain a more compact local structure. Our data indicated that the binding of tropomyosin to actin filaments had no effect on the structure or flexibility of actin observable by this technique.
Recently, a causative association has been made between the ingestion of levotryptophan (L-tryptophan) and the eosinophilia-myalgia syndrome (EMS), a new entity manifested by peripheral blood eosinophilia, myalgias, constitutional symptoms, and cutaneous edema with fibrosis. Contaminated levotryptophan preparations produced at a single manufacturing company between October 1988 and June 1989 have been implicated in all EMS cases. In this study, we analyzed retrospectively 49 patients with cutaneous fibrosis for a history of levotryptophan use. Levotryptophan ingestion prior to the onset of their disease was reported by 11 (65%) of 17 patients with eosinophilic fascilitis (EF), two (20%) of 10 patients with localized scleroderma, and none of 22 patients with systemic sclerosis. The onset of levotryptophan-associated cutaneous disease preceded the availability of contaminated levotryptophan preparations in seven (54%) of 13 patients. One patient with levotryptophan-associated generalized morphea also had lichen sclerosus et atrophicus and acanthosis nigricans, findings not previously reported in patients with EMS. In addition, we compared the clinical and laboratory features of levotryptophan-associated EF and idiopathic EF. Myalgias, muscle weakness, paresthesias, morpheaform plaques, cutaneous ulcers, and livedo reticularis were more common in patients with levotryptophan-associated EF. We conclude that levotryptophan-associated EF and localized scleroderma were present before the presumed date of contaminated levotryptophan availability. The clinical spectrum of cutaneous fibrosis associated with the ingestion of levotryptophan includes generalized morphea and EF, which are similar though not identical to their idiopathic counterparts.
The oxidation of free tryptophan (Trp) and Trp residues in peptides and proteins by hydrogen peroxide as oxidative agent has been used to evaluate Trp losses and the pattern of degradation products formed. Besides free Trp, four Trp-containing peptides and lysozyme were used as substrates in the aqueous model system. The oxidation rate of Trp and the formation of 16 possible degradation compounds were examined using RP-HPLC and UV, fluorescence, and photodiode array detection. The rate of Trp degradation increased from lysozyme to short-chain peptides to unbound Trp. Only approximately 20% of the total Trp loss could be elucidated by the determined Trp degradation compounds. Oxindolylalanine (Oia), 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid (PIC), N-formylkynurenine (NFK), dioxindolylalanine (DiOia), kynurenine (Kyn), and 5-hydroxytryptophan (5-OH-Trp) were identified in this order of quantity as degradation compounds, showing the Trp pyrrole moiety to be most susceptible to oxidation. As short peptides such as H-Ala-Trp-Ala-OH were completely hydrolyzed with immobilized Pronase E, Oia and NFK could be identified as main degradation compounds, as could minor amounts of Kyn, DiOia, PIC, and 5-OH-Trp. Acid (6 M HCl), alkaline (4.2 M NaOH), and enzymatic hydrolyses were compared for the determination of Trp degradation compounds in lysozyme. Kyn, Oia, and DiOia could be detected in the hydrogen peroxide treated protein.
The syntheses of Trp(Nps)-Arg-OMe.HCl (15) [Trp(Nps) = 2-[(o-nitrophenyl)sulfenyl]tryptophan], its three stereoisomers, and their corresponding cyclic analogues are reported. The preparation of Trp(Nps)-Lys-OMe (19) and its cyclic analogue is also described. All these compounds have been designed as analogues of the analgesic dipeptide derivatives X-Trp(Nps)-OMe (1b, X = Arg; 2b, X = Lys). In the case of dipeptides containing Arg or D-Arg, the coupling reactions were achieved via the isobutyl chloroformate and N-methylmorpholine mediated mixed anhydride procedure, while in the case of the Lys analogue, the N,N-dicyclohexylcarbodiimide method was employed. Sulfenylation reactions were carried out with Nps-Cl in acidic media. Cyclization to the diketopiperazines was achieved by using acetic acid as catalyst. The antinociceptive effects of all these new Trp(Nps)-containing dipeptides were evaluated after icv administration in mice, and the effects were compared with those of 1b, 2b, Tyr-Arg (Kyotorphin), and Tyr-D-Arg. The most active compounds, 15 and 19, were found to exhibit a naloxone-reversible antinociceptive effect similar to those of 1b and 2b and approximately 50 and 12.5 times higher than those of Kyotorphin and its D isomer, respectively. Trp(Nps)-D-Arg-OMe.HC1, D-Trp(Nps)-Arg-OMe.HC1, and cyclo[Trp(Nps)-Arg].HC1 were also more effective than Kyotorphin (5, 10, and 10 times, respectively). In view of the structure-activity relationships obtained, several similarities between this series of Trp(Nps)-containing dipeptides and that of Kyotorphin analogues have emerged.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.