Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tryptophan pyrrolooxygenase from wheat germ was separated into three molecular forms by microgranular DEAE-cellulose using a stepwise or a linear gradient elution procedure. In the first case molecular forms A and B were eluted with 10 mM Tris/HCl buffer (pH 7.4) and molecular form C was eluted with 50 mM KCl in the same buffer. The same separation could also be achieved with a linear KCl gradient (0-100 mM) in 10 mM Tris/HCl buffer (pH 7.4). The three molecular forms of tryptophan pyrrolooxygenase oxidized L-, D-, DL-Trp as well as many Trp derivatives with formation of N-formylkynurenyl derivatives. They also efficiently oxidized Trp-Phe, Trp-Tyr, Trp-Ala, Ala-Trp, Trp-Gly, Gly-Trp, Trp-Leu, Leu-Trp, Pro-Trp and Val-Trp, although the dipeptides were oxidized at different rates by the three molecular forms. A number of tryptophyl-containing tetra-, penta-, octa-, nona- and decapeptides were also oxidized. The oligopeptides which were known to have a helical conformation were better substrates than the smaller oligopeptides which were devoid of the conformational factor. The three molecular forms of tryptophan pyrrolooxygenase oxidized the tryptophyl residues of lysozyme, pepsin, chymotrypsin, trypsin and bovine serum albumin. It was found that molecular form A oxidized the more exposed (or hydrophilic) Trp residues of the proteins, while molecular form C also oxidized the Trp residues of a more hydrophobic nature. The three molecular forms were inhibited by chelating agents (alpha, alpha'-dipyridyl, EDTA and omicron-phenanthroline), although they differed in their sensitivities to these agents. Their optimum temperatures and inactivation rates at 65 degrees C was also different.
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PMID:Separation of tryptophan pyrrolooxygenase into three molecular forms. A study of their substrate specificities using tryptophyl-containing peptides and proteins. 369 18

The photoreactive arylsufenyl chloride 2-nitro-4-azidophenylsulfenyl chloride (2,4-NAPS-Cl) has been used for the selective modification of tryptophan in Kunitz's soybean trypsin inhibitor (STI). The ultraviolet absorption spectrum and amino acid analysis of 2,4-NAPS-STI indicated that only one of the two tryptophans, 93 or 117, present in STI was modified. Amino acid analysis of the two separated CNBr-cleavage products of 2,4-NAPS-STI showed that only tryptophan 93 underwent modification. 2,4-NAPS-STI fully retained its inhibitory activity against trypsin. The covalent attachment of 2,4-NAPS-STI to tritiated trypsin after photolysis was demonstrated by exclusion chromatography on Sephadex G-50 in the presence of guanidine hydrochloride. Photoreactive derivatives of the Bowman-Birk trypsin-chymotrypsin inhibitor (BBI) from soybeans and of CI, the trypsin-chymotrypsin inhibitor from chick peas were prepared by selective modification of the epsilon-amino groups of 2,4(5)-NAPS-Cl. The ultraviolet absorption spectra of the photolabeled inhibitors indicated that three out of the five lysines of BBI and one of the seven lysines of CI were modified. The inhibitory activity of the modified inhibitors towards trypsin and chymotrypsin was not reduced even after photolysis. The specific lysine residues that constitute the trypsin-inhibitory sites of BBI and CI did not react with the photoreactive reagents. Further modification of the photoreactive derivatives of BBI and CI with maleic anhydride, directed towards the trypsin-reactive sites, resulted in almost complete loss of trypsin-inhibiting activity without reducing the ability to inhibit chymotrypsin. A pronounced potentiation effect (approximately 2x) of the chymotrypsin inhibiting activity was noted for 2,5-NAPS-CI and it was retained even after maleylation followed by photolysis, raising the possibility of exposure of an additional chymotrypsin inhibitory site in CI.
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PMID:Photoreactive, active derivatives of trypsin and chymotrypsin inhibitors from soybeans and chickpeas. 379 89

The tryptophan environments in crystalline alpha-chymotrypsin were investigated by fluorescence. The heterogeneous emission from this multitryptophan enzyme was resolved by time-correlated fluorescence spectroscopy. The fluorescence decays at 296-nm laser excitation and various emission wavelengths could be characterized by a triple-exponential function with decay times tau 1 = 150 +/- 50 ps, tau 2 = 1.45 +/- 0.25 ns, and tau 3 = 4.2 +/- 0.4 ns. The corresponding decay-associated emission spectra of the three components had maxima at about 325, 332, and 343 nm. The three decay components in this enzyme can be correlated with X-ray crystallographic data [Birktoft, J.J., & Blow, D.M. (1972) J. Mol. Biol. 68, 187-240]. Inter- and intramolecular tryptophan-tryptophan energy-transfer efficiencies in crystalline alpha-chymotrypsin were computed from the accurately known positions and orientations of all tryptophan residues. These calculations indicate that the three fluorescence decay components in crystalline alpha-chymotrypsin can be assigned to three distinct classes of tryptophyl residues. Because of the different proximity of tryptophan residues to neighboring internal quenching groups, the decay times of the three classes are different. Decay tau 1 can be assigned to Trp-172 and Trp-215 and tau 2 to Trp-51 and Trp-237, while the tryptophyl residues 27, 29, 141, and 207 all have decay time tau 3.
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PMID:Study of the time-resolved tryptophan fluorescence of crystalline alpha-chymotrypsin. 381 86

The amino acid sequence of rabbit skeletal muscle heat-stable inhibitor of the cAMP-dependent protein kinase has been determined by microsequencing techniques. Proof of the structure involved a series of nonoverlapping tryptic fragments for primary identification of 86% of the amino acids. Complementary fragments generated by cleavage with chymotrypsin, Staphylococcus aureus V8 proteinase, and mast cell proteinase II contributed to proof of the structure. The inhibitor is a single polypeptide chain of 75 residues and has a molecular weight of 7829. It lacks tryptophan, proline, and sulfur-containing amino acids. The amino terminus of the inhibitor is blocked by an unidentified group. The amino-terminal region of the molecule contains the kinase inhibitory domain, and synthetic peptides based on the sequence of residues 11-30 are potent competitive inhibitors of the cAMP-dependent protein kinase [Scott, J. D., Fischer, E. H., Demaille, J. G. & Krebs, E. G. (1985) Proc. Natl. Acad. Sci. USA 82, 4379-4383]. Residues 14-22 show considerable homology to the "hinge-regions" of the regulatory subunits of the cAMP-dependent protein kinase. The remainder of the molecule shows no similarity to the known amino acid sequence of any protein.
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PMID:Amino acid sequence of the heat-stable inhibitor of the cAMP-dependent protein kinase from rabbit skeletal muscle. 389 70

A thermolytic hydrolysis of maleinated fragment F1 has been performed, resulted in isolation of 44 peptides; their complete amino acid sequence has been determined. Non-overlapping thermolytic peptides of fragment F1 involve 178 amino acid residues, which comprises about 71% of its amino acid sequence. Also, the cleavage and structural investigation of some tryptophan-containing peptides obtained from the limited trypsinolysis of fragment F1 were carried out; reconstitution of the polypeptide chain of the fragment is completed. The cyanogen bromide cleavage of carboxymethylated cytochrome P-450 was achieved and 17 peptides, comprising almost the whole polypeptide chain of the protein molecule (91%), was isolated. To investigate structure of the cyanogen bromide peptides, we hydrolysed them at tryptophan residues with trypsin, chymotrypsin, proteinase from Staphylococcus aureus, and BNPS-skatole. The data obtained and those published earlier led to the complete primary structure of the cholesterol-hydroxylating cytochrome P-450. The proteins polypeptide chain consists of 481 amino acid residues and has the precise molecular mass 56 407.7.
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PMID:[Primary structure of 20S,22R-cholesterol-hydroxylating cytochrome P-450 from bovine adrenal cortex mitochondria. IV. Structure of peptides of thermolytic and limited tryptic hydrolysis of the fragment F1; peptides of cyanogen bromide hydrolysis of cytochrome P-450. Complete amino acid sequence]. 390 59

The complete amino acid sequence of FBP aldolase from Drosophila melanogaster has been determined. The enzyme contains four identical subunits of 360 amino acid residues. The primary structure of the monomer was established using automated Edman degradation on fragments prepared by CNBr-cleavage, by partial acid cleavage at the unique Asp-Pro bond and by oxidative cleavage at the three tryptophan residues. Manual Edman-Chang degradation was used on smaller peptides obtained by digestion with Staphylococcus aureus V8 protease, trypsin or chymotrypsin. The primary structure of Drosophila aldolase exhibits very extensive homology with the sequence of rabbit muscle aldolase (71% identity), thus explaining the early observation that Drosophila and mammalian aldolases form active interspecies hybrid quaternary structures (Brenner-Holzach, O. and Leuthardt, F., Eur. J. Biochem. (1972) 31, 423-426).
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PMID:Amino acid sequence of an invertebrate FBP aldolase (from Drosophila melanogaster). 391 28

The complete amino acid sequence of kappa-bungarotoxin, a neurotoxin isolated from the venom of the banded krait Bungarus multicinctus, has been determined by automated Edman analyses of the intact protein and peptides derived from digests with trypsin and chymotrypsin. kappa-Bungarotoxin consists of a single polypeptide chain of 66 amino acids with a molecular weight of 7313. It contains 10 cysteinyl residues, presumably arranged in 5 disulfide bonds, and is completely devoid of methionine and tryptophan. The amino acid sequence of kappa-bungarotoxin shows greatest homology to the curaremimetic postsynaptic long neurotoxins of which alpha-bungarotoxin is also a member. However, there are some striking differences between kappa-bungarotoxin and other members of this group which may explain its unusual ability to block neuronal acetylcholine receptors.
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PMID:kappa-Bungarotoxin: complete amino acid sequence of a neuronal nicotinic receptor probe. 398 93

Tryptic cleavage of EF-2, molecular mass 93 kDa, produced an 82-kDa polypeptide and a 10-kDa fragment, which was further degraded. By a slower reaction the 82-kDa polypeptide was gradually split into a 48-kDa and a 34-kDa fragment. Similarly, treatment with chymotrypsin resulted in the formation of an 82-kDa polypeptide and a small fragment. In contrast to the tryptic 82-kDa polypeptide the corresponding chymotryptic cleavage product was relatively resistant to further attack. The degradation of the 82-kDa polypeptide with either trypsin or chymotrypsin was facilitated by the presence of guanosine nucleotides, indicating a conformational shift in native EF-2 upon nucleotide binding. No effect was observed in the presence of ATP, indicating that the effect was specific for guanosine nucleotides. After affinity labelling of native EF-2 with oxidized [3H]GTP and subsequent trypsin treatment the radioactivity was recovered in the 48-kDa polypeptide showing that the GTP-binding site was located within this part of the factor. Correspondingly, tryptic degradation of EF-2 labelled with [14C]NAD+ in the presence of diphtheria toxin showed that the site of ADP-ribosylation was within the 34-kDa polypeptide. By cleavage with the tryptophan-specific reagent N-chlorosuccinimide the site of ADP-ribosylation could be located at a distance of 40-60 kDa from the GTP-binding site and about 4-11 kDa from the nearest terminus.
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PMID:Localization of the sites of ADP-ribosylation and GTP binding in the eukaryotic elongation factor EF-2. 398 90

Spectrophotometric measurement was found to be a sensitive method for evaluating the stability of the chymotrypsin inhibitor from the winged bean. The thermal stability of this protein in aqueous solution was much greater at pH 3 than at pH 8 or pH 11. Evidence from u.v. absorption and from circular dichroism indicated that irreversible conformation changes occurred at higher temperature (greater than 70 degrees). Circular dichroism and optical rotatory dispersion studies at pH 8 show that the inhibitor is rich in beta-structure and virtually devoid of alpha-helix in aqueous solution. We conclude from experiments with denaturing solvents that the inhibitor is very stable and that high concentrations of denaturant are required before unfolding occurs. Chemical modification experiments with tetranitromethane were consistent with a tight stable structure; even in 6M guanidine hydrochloride only three of the five tyrosine residues in the inhibitor molecule were nitrated. However, tyrosine does not seem to be implicated at the reactive site of the inhibitor. Interaction of the inhibitor with alpha-chymotrypsin and chymotrypsin B was also followed by difference spectroscopy in the ultraviolet region. Difference spectra were detected that were characteristic of changes in the environment of both tyrosine and tryptophan chromophores. Comparison of the spectral data obtained for the interaction of the inhibitor with bovine alpha-chymotrypsin and with chymotrypsin B indicated that a tryptophan residue may be involved at the reactive site of the inhibitor. Spectral changes were also detected for the interaction between the chymotrypsin inhibitor and trypsin, although it is well established that the specificity of this inhibitor is restricted to the chymotrypsins.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Conformation and stability of the chymotrypsin inhibitor from winged bean seed (Psophocarpus tetragonolobus (L.) DC). 401 22

The effects of various chemical and enzymatic treatments on the biological activity of porcine luteinizing hormone-releasing hormone (LH-RH) are described. This experiment was performed before the elucidation of the structure of LH-RH. LH-RH activity was abolished by the following endopeptidases: chymotrypsin, subtilisin, papain, and thermolysin, but not by pepsin or trypsin. Exopeptidases did not affect LH-RH activity, but a purified preparation of pyrolidone carbosylpeptidase did. The amino acid sequence of LH-RH/FSH-RH was established to be (pyro)Glu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-Amine. This decapeptide lacks both the Amine terminus and the COOH terminus. Its Amine-terminal dipeptide sequence,(pyro)Glu-His, is similar to that of tyrotropin-releasing hormone. The lack of inactivation by the exopeptidases is in good agreement with these findings. Treatment with various chemical reagents showed that tyrosine, histidine, tryptophan, and arginine in LH-RH are important for its biological activity. Nitrous acid and Edman degradation did not inactivate LH-RH. These results are also in agreement with the determined structure of LH-RH. This hormone showed a high follicle-stimulating hormone-releasing hormone (FSH-RH) activity. The inactivation of LH-RH was always accompanied by a loss of FSH-RH activity. These experiments also shed some light on the structure-activity relationship of this hormone.
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PMID:Studies on the properties of hypothalamic luteinizing hormone-releasing hormone. 494 14


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