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)

Human liver type III collagen was prepared by limited pepsin digestion, differential salt precipitation, and carboxymethylcellulose chromatography. Cyanogen bromide digestion of purified type III collagen chains yielded nine distinct peptides. Three peptides, alpha1(III)-CB3, alpha1(III)-CB7, and alpha1(III)-CB6, were isolated by carboxymethylcellulose chromatography and Sephadex G-50 SF gel filtration. Automated Edman degradation together with selective hydroxylamine cleavage and chymotrypsin and trypsin digestion enabled determination of their complete amino acid sequence. Compared with type I collagen, the data show tentative homology of alpha1(III)-CB3 with alpha1(I)-CB1, alpha1(I)-CB2, and alpha1(I)-CB4; alpha1(III)-CB7 with alpha1(I)-CB5; and alpha1(III)-CB6 with the amino-terminal portion of alpha1(I)-CB8. Close interspecies homology was found between the sequences presented here with 90 residues of alpha1(III)-CB3 and 26 of alpha1(III)-CB8 of calf aorta. The present study establishes the amino acid sequence of 229 residues near the amino terminus or nearly one-quarter of the type III collagen chains. The disaccharide, Glc-Gal, was convalently bound to hydroxylysine at a position corresponding to the same location in the alpha1(I) chain.
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PMID:Covalent structure of collagen: amino acid sequence of cyanogen bromide peptides from the amino-terminal segment of type III collagen of human liver. 55 35

The stoichiometry of the phosphorylation of rabbit muscle glycogen synthase by casein/glycogen synthase kinase-1 (CK-1) depended on the concentration of protein kinase in the assay and reached values of 7-8 mol/mol subunit at high concentrations. Phosphorylation by CK-1 above 4 mol/mol subunit promoted a further decrease of glycogen synthase activity when determined by the low glucose-6-phosphate/high glucose-6-phosphate activity ratio assay. Analysis by limited proteolysis with trypsin and chymotrypsin showed that all of the regions in glycogen synthase phosphorylated by casein/glycogen synthase kinase-2 (CK-2), the catalytic subunit of cyclic AMP-dependent protein kinase (A-kinase), FA/glycogen synthase kinase-3 (FA/GSK-3) and phosphorylase b kinase were also phosphorylated by CK-1. Digestion with CNBr of glycogen synthase phosphorylated by CK-1 revealed the presence of the two phosphopeptides also labeled by the other protein kinases, the largest phosphopeptide (CB2) containing more phosphorylation sites for CK-1 than the smallest one (CB1). Three phosphopeptides (CB2-c, CB2-d and CB2-e) were obtained by trypsinization of CB2 phosphorylated by CK-1. None of them coincided with those labeled by A-kinase, a fact that was confirmed by the additivity of the effect of both protein kinases. In contrast, CB2-d comigrated with the peptide phosphorylated by FA/GSK-3, and CB2-e with that labeled by CK-2, whereas CB2-c would correspond to a new phosphopeptide.
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PMID:Phosphorylation of rabbit muscle glycogen synthase by casein/glycogen synthase kinase-1 (CK-1). Stoichiometry and distribution of the phosphorylation sites on the glycogen synthase subunit. 301 47

Cyanogen bromide (CB) cleavage of Neurospora tyrosinase resulted in four major fragments, CB1 (222 residues), CB2 (82 residues), CB3 (68 residues), and CB4 (35 residues), and one minor overlap peptide CB2-4 (117 residues) due to incomplete cleavage of a methionylthreonyl bond. The sum of the amino acid residues of the four major fragments matches the total number of amino acid residues of the native protein. The amino acid sequences of the cyanogen bromide fragments CB2, CB3, and CB4 were determined by a combination of automated and manual sequence analysis on peptides derived by chemical and enzymatic cleavage of the intact and the maleylated derivatives. The peptides were the products of cleavage by mild acid hydrolysis, trypsin, pepsin, chymotrypsin, thermolysin, and Staphylococcus aureus protease V8. The cyanogen bromide fragment CB1 was found to contain two unusual amino acids whose chemical structure will be presented in the following paper.
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PMID:Primary structure of tyrosinase from Neurospora crassa. I. Purification and amino acid sequence of the cyanogen bromide fragments. 621 Jun 95

Reverse-phase high-pressure liquid chromatography has been used for the purification of some large cyanogen bromide peptides from flavocytochrome b2 fragment alpha. Acetonitrile gradients at acid and/or neutral pH using mu Bondapak C18 columns were useful for the smaller peptides (43 and 67 residues). The two larger ones, alpha CB1 and alpha CB2, could only be separated from each other by trifluoroacetic acid/1-propanol gradients on mu Bondapak-CN columns. The various systems tested are presented and compared. The elucidation of the amino acid sequence of alpha CB2 (95 residues), alpha CB3 (67 residues) and alpha CB4 (43 residues) is described. The fragments were digested with trypsin, chymotrypsin and Staphylococcus aureus V8 protease as necessary. Fragment alpha CB2 was also cleaved at the unique tryptophanyl bond with cyanogen bromide. Peptides were fractionated by Sephadex chromatography, thin-layer finger-printing and/or high-pressure liquid chromatography. Peptides were sequenced mostly in the liquid phase sequenator. The cyanogen bromide peptides could be ordered using information obtained previously, as well as additional data obtained in this work. Together with the previous elucidation of cytochrome b2 core sequence and of the hinge region [Guiard, B. and Lederer, F. (1976) Biochimie (Paris) 58, 305--316; Ghrir, R. and Lederer, F. (1981) Eur. J. Biochem. 120, 279--287], the present results enable us to present the complete sequence of fragment alpha (314 residues) with only three overlaps missing between cyanogen bromide peptides. Sequence comparisons with other known flavoproteins do not indicate any noticeable similarity. Structural predictions indicate an alteration of alpha helices and beta structure. The possibility that the non-heme-binding portion of fragment alpha could constitute a flavin-binding domain is discussed.
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PMID:Primary structure of flavocytochrome b2 from baker's yeast. Purification by reverse-phase high-pressure liquid chromatography and sequencing of fragment alpha cyanogen bromide peptides. 636 48

Glycogen synthase is a substrate for five distinct protein kinases in skeletal muscle which phosphorylate seven different serine residues on the enzyme. Cyclic-AMP-dependent protein kinase phosphorylates sites 1a, 1b and 2, phosphorylase kinase, site 2, glycogen synthase kinase 3, sites 3a, 3b and 3c, glycogen synthase kinase 4, site 2 and glycogen synthase kinase 5 site 5. Site 2 is seven residues from the N-terminus of glycogen synthase and is located in a cyanogen bromide peptide termed CB1 (apparent Mr = 9000). The other six phosphorylation sites are located in a cyanogen bromide peptide termed CB2 (apparent Mr = 24 000) at the C-terminal end of the molecule. The sequence of the N-terminal 123 residues of peptide CB2, has been completed. Sites 3a, 3b, 3c, 5, 1a and 1b are located at residues 30, 34, 38, 46, 87 and 100 from the N-terminus of CB2 respectively. Site 1a is the next serine residue after site 5. The region surrounding sites 3a, 3b and 3c is very rich in proline residues while that surrounding sites 1a and 1b contains many serine and threonine residues. The 23 residues following site 5 contain 15 aspartic acid and glutamic acid residues, while the region immediately N-terminal to site 1a is very basic. The whole region is remarkably hydrophilic and is the region at which the native enzyme is attacked by proteinases. The sites at which glycogen synthase is cleaved by trypsin, chymotrypsin and thermolysin have been identified. The finding that trypsin cleaves the enzyme C-terminal to site 3c while chymotrypsin cleaves N-terminal to site 3a has formed the basis of a simple procedure for determining the state of phosphorylation of the seven serine residues in vivo [Parker, P.J., Embi, N., Caudwell, F.B., and Cohen, P. (1982) Eur. J. Biochem. 124, 47-55].
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PMID:Multisite phosphorylation of glycogen synthase from rabbit skeletal muscle. Organisation of the seven sites in the polypeptide chain. 680 97

The effects of cannabinoid receptor agonists on the non-adrenergic non-cholinergic (NANC) inhibitory responses to electrical field stimulation in guinea-pig trachea were assessed. R-(+)-[2,3-dihydro-5-methyl-3-[(morpholilinyl) methyl]pyrrolo [1,2,3-de]-1,4-benzoxazin-6-yl]-(1-naphthalenyl)methanone mesylate (WIN 55,212-2; 10(-5) M) significantly enhanced the frequency-dependent response to electrical stimulation. The same concentration of R-(N)-(2-hydroxy-1-methylethyl)-5Z,8Z,11Z,14Z-eicosatetraenamide (R(+)methanandamide) and 1-propyl-2-methyl-3-(1-naphthoyl)indole (JWH-015) did not affect significantly the electrically induced inhibitory NANC responses. The effect of WIN 55,212-2 was not modified by the cannabinoid CB1 and CB2 receptor-selective antagonists, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride (SR141716A; 10(-5) M) and N-(1S)-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR 144528; 10(-5) M), respectively. Moreover, the nitric oxide synthase inhibitor, L-NG-nitro-arginine methyl ester (L-NAME; 10(-4) M), but not the peptidase, alpha-chymotrypsin (2 U/ml), blocked the effect of WIN 55,212-2. Postsynaptically, WIN 55,212-2 did not produce any change of tracheal smooth muscle tone, either basal or histamine-induced, and did not interfere with the relaxant activity of the nitric oxide donor, sodium nitroprusside (10(-8)-10(-4) M). In conclusion, our results suggest that (a) cannabinoid CB1 and CB2 receptor stimulation does not alter the inhibitory NANC transmission in guinea-pig trachea, and (b) WIN 55,212-2 potentiates the NO-mediated component of the NANC relaxant response to electrical stimulation through a cannabinoid receptor-independent mechanism.
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PMID:Effects of cannabinoids on non-adrenergic non-cholinergic-mediated relaxation in guinea-pig trachea. 1295 67

The CB1 and CB2 cannabinoid receptors belong to the GPCR superfamily and are associated with a variety of physiological and pathophysiological processes. Both receptors, with several lead compounds at different phases of development, are potentially useful targets for drug discovery. For this reason, fully elucidating the structural features of these membrane-associated proteins would be extremely valuable in designing more selective, novel therapeutic drug molecules. As a first step toward obtaining information on the structural features of the drug-receptor complex, we describe the full mass spectrometric (MS) analysis of the recombinant human cannabinoid CB2 receptor. This first complete proteomic characterization of a GPCR protein beyond rhodopsin was accomplished by a combination of several LC/MS approaches involving nanocapillary liquid chromatography, coupled with either a quadrupole-linear ion trap or linear ion trap-FTICR mass spectrometer. The CB2 receptor, with incorporated N-terminal FLAG and C-terminal HIS6 epitope tags, was functionally expressed in baculovirus cells and purified using a single step of anti-FLAG M2 affinity chromatography. To overcome the difficulties involved with in-gel digestion, due to the highly hydrophobic nature of this membrane-associated protein, we conducted in-solution trypsin and chymotrypsin digestions of purified and desalted samples in the presence of a low concentration of CYMAL5. This was followed by nanoLC peptide separation and analysis using a nanospray ESI source operated in the positive mode. The results can be reported confidently, based on the overlapping sequence data obtained using the highly mass accurate LTQ-FT and the 4000 Q-Trap mass spectrometers. Both instruments gave very similar patterns of identified peptides, with full coverage of all transmembrane helices, resulting in the complete characterization of the cannabinoid CB2 receptor. Mass spectrometric identification of all amino acid residues in the cannabinoid CB2 receptor is a key step toward the "Ligand Based Structural Biology" approach developed in our laboratory for characterizing ligand binding sites in GPCRs using a variety of covalent cannabinergic ligands.
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PMID:Comprehensive proteomic mass spectrometric characterization of human cannabinoid CB2 receptor. 1747 60

This study was conducted to optimize the expression of human CB2 cannabinoid receptors in methylotrophic yeast Pichia pastoris (P. pastoris). Two major species of expressed CB2 proteins were seen on Western blot, i.e., a 42 kDa band which matches the calculated molecular weight for tagged CB2, and a 52/55 kDa doublet. Treatment of membranes with N-glycosidase F or inclusion of tunicamycin in the culture medium during induction resulted in the disappearance of the 55 kDa, but not the 52 kDa band, suggesting that the 3 kDa extra in the 55 kDa band is due to N-glycosylation, but the 10 kDa extra in the 52 kDa band is not due to N-glycosylation. Anti-FLAG M1 antibody had a much higher preference for the 42 kDa band over the 52/55 kDa doublet, and a 10 kDa fragment recognized by anti-FLAG M2 antibody was generated by CNBr digestion of the 52/55 doublet. These data strongly support the hypothesis that the 10 kDa increase in molecular weight was due to unprocessed alpha-factor sequence. This conclusion was further validated by finding several peptide sequences for alpha-factor fragments at the N-terminal of the CB2 receptor using pepsin/chymotrypsin digestion and LC/MS/MS approaches. Importantly, unprocessed alpha-factor was found to be associated with poor ligand binding. In addition, controlling the level of CB2 protein expression was found to be critical for minimizing the presence of unprocessed alpha-factor sequence. The information gained from this study should aid the proper expression of not only CB2 receptor but also other members of the GPCR family in P. pastoris.
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PMID:Biochemical and mass spectrometric characterization of the human CB2 cannabinoid receptor expressed in Pichia pastoris--importance of correct processing of the N-terminus. 1750 8

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