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)

We report here the identification of the amino acid residue which forms the covalent intermediate in the catalytic mechanism of bovine intestinal 5'-nucleotide phosphodiesterase and the sequence of the neighboring amino acids. The active site of 5'-nucleotide phosphodiesterase was labeled using thymidine 5'-[alpha-32P]triphosphate as substrate. A single labeled cyanogen bromide peptide was isolated using reversed-phase high performance liquid chromatography. After subdigestion with endoproteinase Lys-C and chymotrypsin, the entire amino acid sequence of the 60-residue active site peptide was obtained using automated Edman degradation. All of the radioactivity of the active site peptide was localized to a hexapeptide with sequence Thr-Phe-Pro-Asn-His-Tyr. Phosphoamino acid analysis of this peptide indicated that the labeled residue was threonine. We are not aware of any other enzymes in which threonine is phosphorylated as a covalent intermediate in the catalytic mechanism.
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PMID:Amino acid sequence of the active site peptide of bovine intestinal 5'-nucleotide phosphodiesterase and identification of the active site residue as threonine. 298 87

Epidermal growth factor (EGF) isolated from the submaxillary gland of the rat (rEGF) is missing the COOH-terminal five residues present in both mouse and human EGF. rEGF competes for the binding of 125I-labelled mEGF to human carcinoma cells with the same affinity as mEGF. rEGF and mEGF have identical mitogenic activities on mouse 3T3 fibroblasts, thus the C-terminal region of the sequence is not necessary for the in vitro activity of EGF. Using reversed-phase high-performance liquid chromatography, four molecular forms of EGF have been extracted from rat submaxillary glands. These forms represent rEGF, rEGF(2-48), rEGF(3-48) and rEGF(4-48); all forms appear to be equipotent in both the receptor binding and mitogenic assays. The isoelectric points of these rEGFs are in the range of pH 5.1 to 5.2. The primary structure of rEGF was determined from approximately 10 micrograms protein by sequence analysis of the intact molecule and fragments obtained from the reduced and alkylated protein by chemical cleavage with CNBr and enzymic cleavage with chymotrypsin and a proline-specific endopeptidase. Subnanomole amounts of generated peptides were purified to homogeneity by reversed-phase microbore high-performance liquid chromatography and analysed by automated Edman degradation in a gas-phase sequencer. There are 48 amino acid residues in the complete polypeptide chain which lacks alanine, phenylalanine, lysine and tryptophan. The amino acid sequence of rat epidermal growth factor is: Asn-Ser-Asn-Thr-Gly-Cys-Pro-Pro-Ser-Tyr-Asp-Gly-Tyr-Cys-Leu-Asn- Gly-Gly-Val-Cys-Met-Tyr-Val-Glu-Ser-Val-Asp-Arg-Tyr-Val-Cys-Asn-Cys -Val-Ile-Gly-Tyr-Ile-Gly-Glu-Arg-Cys-Gln-His-Arg-Asp-Leu-Arg. The calculated relative molecular mass from the sequence analysis is 5377.
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PMID:Rat epidermal growth factor: complete amino acid sequence. Homology with the corresponding murine and human proteins; isolation of a form truncated at both ends with full in vitro biological activity. 300 Jul 82

Purified phospholamban isolated from canine cardiac sarcoplasmic reticulum vesicles was subjected to proteolysis and peptide mapping to localize the different sites of phosphorylation on the protein and to gain further information on its subunit structure. Five different proteases (trypsin, papain, chymotrypsin, elastase, and Pronase) degraded the oligomeric 27-kDa phosphoprotein into a major 21-22-kDa protease-resistant fragment. No 32P was retained by this protease-resistant fragment, regardless of whether phospholamban had been phosphorylated by cAMP-dependent protein kinase, Ca2+/calmodulin-dependent protein kinase, or protein kinase C. Phosphoamino acid analysis and thin-layer electrophoresis of liberated phosphopeptides revealed that 1 threonine and 2 serine residues were phosphorylated in phospholamban and that 1 of these serine residues and the threonine residue were in close proximity. Only serine was phosphorylated by cAMP-dependent protein kinase, whereas Ca2+-calmodulin-dependent protein kinase phosphorylated exclusively threonine. The results demonstrate that phospholamban has a large protease-resistant domain and a smaller protease-sensitive domain, the latter of which contains all of the sites of phosphorylation. The 21-22-kDa protease-resistant domain, although devoid of incorporated 32P, was completely dissociated into identical lower molecular weight subunits by boiling in sodium dodecyl sulfate, suggesting that this region of the molecule promotes the relatively strong interactions that hold the subunits together. The data presented lend further support for a model of phospholamban structure in which several identical low molecular weight subunits are noncovalently bound to one another, each containing one site of phosphorylation for cAMP-dependent protein kinase and another site of phosphorylation for Ca2+/calmodulin-dependent protein kinase.
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PMID:Proteolytic cleavage of phospholamban purified from canine cardiac sarcoplasmic reticulum vesicles. Generation of a low resolution model of phospholamban structure. 300 93

Previous studies of the attachment of encephalomyocarditis (EMC) virus to human erythrocytes concluded that the glycophorins, a family of human erythrocyte sialoglycoproteins, act as EMC virus receptors. Evidence is presented that the major glycophorin species, glycophorin A, is the receptor for EMC virus attachment to human erythrocytes. Comparison of the structures of glycophorins A and B and sialoglycopeptides released by chymotrypsin and trypsin treatment of erythrocytes confirmed our previous suggestion (A. T. H. Burness and I. U. Pardoe, J. Gen. Virol. 64:1137-1148, 1983) that attachment of EMC virus to glycophorin A involves the region containing amino acids 35 to approximately 70 (numbered from the NH2 terminus), four of which (amino acids 37, 44, 47, and 50) are glycosylated. In addition, we provide evidence that the segment containing amino acids 35 to 39 with an oligosaccharide side chain on threonine-37 is particularly important for EMC virus attachment.
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PMID:Site of attachment of encephalomyocarditis virus on human erythrocytes. 301 41

Evidence is presented for rapid, limited proteolysis of protein Z by alpha-thrombin. This alpha-thrombin-catalyzed proteolysis of protein Z occurred at a single peptide linkage, between Arg-365 and Gly-366, located in the COOH-terminal portion. The resulting NH2-terminal large fragment (PZt) and the COOH-terminal peptide (C-peptide) were isolated and chemically characterized. The C-peptide consisted of 31 amino acid residues including one galactosamine-type Thr residue and was assigned to the position from Gly-366 to the COOH-terminal residue of Val-396 in protein Z. The NH2-terminal large fragment, PZt, constituted the remainder of protein Z. The abilities to bind calcium of intact protein Z, PZt, and the derivative of protein Z devoid of the NH2-terminal gamma-carboxyglutamic acid (Gla) domain (Gla-domainless), prepared with the known chymotrypsin treatment, were examined by equilibrium dialysis. The results indicated that intact protein Z and PZt contain four calcium binding sites with dissociation constants of 0.1 mM. Moreover, the Scatchard plot analysis showed positive cooperativity, suggesting the presence of at least two initial sites for calcium binding. In contrast, the Gla-domainless protein Z had no calcium binding site, indicating that the domain of protein Z functional for calcium binding occurs within the NH2-terminal Gla domain. This differed from factor X, factor IX, protein S, and protein C, all of which contain one or two calcium binding site(s) independent on their Gla-domains.
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PMID:A characteristic property of vitamin K-dependent plasma protein Z. 307 28

At relatively high concentrations of myosin light chain kinase, a second site on the 20,000-dalton light chain of smooth muscle myosin is phosphorylated (Ikebe, M., and Hartshorne, D. J. (1985) J. Biol. Chem. 260, 10027-10031). In this communication the site is identified and kinetics associated with its phosphorylation and dephosphorylation are described. The doubly phosphorylated 20,000-dalton light chain from turkey gizzard myosin was hydrolyzed with alpha-chymotrypsin and the phosphorylated peptide was isolated by reverse phase chromatography. Following amino acid analyses and partial sequence determinations the second site of phosphorylation is shown to be threonine 18. This site is distinct from the threonine residue phosphorylated by protein kinase C. The time courses of phosphorylation of serine 19 and threonine 18 in isolated light chains follow a single exponential indicating a random process, although the phosphorylation rates differ considerably. The values of kcat/Km for serine 19 and threonine 18 for isolated light chains are 550 and 0.2 min-1 microM-1, respectively. With intact myosin, phosphorylation of serine 19 is biphasic; kcat/Km values are 22.5 and 7.5 min-1 microM-1 for the fast and slow phases, respectively. In contrast, phosphorylation of threonine 18 in intact myosin is a random, but markedly slower process, kcat/Km = 0.44 min-1 microM-1. Dephosphorylation of doubly phosphorylated myosin (approximately 4 mol of phosphate/mol of myosin) and isolated light chains (approximately 2 mol of phosphate/mol of light chain) follows a random process and dephosphorylation of the serine 19 and threonine 18 sites occurs at similar rates.
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PMID:Identification, phosphorylation, and dephosphorylation of a second site for myosin light chain kinase on the 20,000-dalton light chain of smooth muscle myosin. 307 56

The amino acid sequences surrounding three major phosphorylation sites in rat and bovine synapsin I have been determined by employing automated gas-phase sequencing and manual Edman degradation of purified phosphopeptide fragments. Site 1 is a serine residue phosphorylated by cAMP-dependent protein kinase and by calcium/calmodulin-dependent protein kinase I. The sequence around site 1 was derived from tryptic/chymotryptic phosphopeptides and overlapping cyanogen bromide cleavage fragments. This sequence, identical in rat and bovine synapsin I, is Asn-Tyr-Leu-Arg-Arg-Arg-Leu-Ser(P)-Asp-Ser-Asn-Phe-Met. Site 1 is located at the NH2 terminus of the protein, within the collagenase-resistant head region. Sites 2 and 3 are serine residues phosphorylated by calcium/calmodulin-dependent protein kinase II. The sequences surrounding bovine site 2 and site 3 were derived from tryptic phosphopeptides and overlapping fragments generated by cleavage with chymotrypsin, collagenase, and endoproteinase Lys-C. The sequence around bovine site 2 is Thr-Arg-Gln-Thr-Ser(P)-Val-Ser-Gly-Gln-Ala-Pro-Pro-Lys, and the sequence around bovine site 3 is Thr-Arg-Gln-Ala-Ser(P)-Gln-Ala-Gly-Pro-Met-Pro-Arg. Sites 2 and 3 are located within the COOH-terminal, collagenase-sensitive tail region of the molecule, separated by 36 amino acids. The sequences surrounding rat site 2 and site 3 were derived from tryptic phosphopeptides. The sequence around rat site 2 is Gln-Ala-Ser(P)-Ile-Ser-Gly-Pro-Ala-Pro-Pro-Lys, and the sequence around rat site 3 is Gln-Ala-Ser(P)-Gln-Ala-Gly-Pro-Gly-Pro-Arg. Thus, the sequences surrounding the four sites that are phosphorylated by calcium/calmodulin-dependent protein kinase II, namely sites 2 and 3 in rat and bovine synapsin I, exhibit a high degree of homology.
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PMID:Amino acid sequences surrounding the cAMP-dependent and calcium/calmodulin-dependent phosphorylation sites in rat and bovine synapsin I. 311 71

Limited chymotryptic digestion of whole tau proteins produced a fragment of Mr 14,000 (CT14), which was able to bind to microtubules reconstituted from tubulin alone in the presence of taxol. This fragment was also found to persist in microtubules when microtubules consisting of tau proteins and tubulin were digested by chymotrypsin. Analysis of amino acid composition revealed that CT14 was rich in lysine and proline residues, suggesting unique structure of microtubule-binding domain of tau proteins. Amino-terminal sequence of CT14 was determined to be Ser-Ser-Pro-Gly-Ser-Pro-Gly-Thr-Pro-Gly-Ser-Arg-Ser-Arg-X-Pro-Ser-Leu-Pr o. No heterogeneity was detected in this amino-terminal sequence of 19 residues. Five species of polypeptides consisting of tau proteins were separated from each other by gel electrophoresis and subjected to chymotryptic digestion. CT14 was produced from each of the tau polypeptides by chymotryptic digestion, indicating that all tau polypeptides have a common microtubule-binding domain.
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PMID:Microtubule-binding domain of tau proteins. 313 25

The complete amino acid sequence of the mating pheromone Er-1 purified from Euplotes raikovi homozygous for mat-1 was determined by automated Edman degradation of the whole protein and peptides generated by cyanogen bromide, trypsin, Staphylococcus aureus V8 protease, and chymotrypsin. The proposed sequence is: Asp-Ala-Cys-Glu-Gln-Ala-Ala-Ile-Gln-Cys-Val-Glu-Ser-Ala-Cys-Glu-Ser-Leu- Cys-Thr-Glu-Gly-Glu-Asp-Arg-Thr-Gly-Cys-Tyr-Met-Tyr-Ile-Tyr-Ser-Asn-Cys- Pro-Pro-Tyr-Val The calculated molecular weight is 4411.0, which is in agreement with the averaged mass of 4410.2 obtained by fission fragment ionization mass spectrometry. Previously reported values of the native molecular weight, determined by gel filtration, have ranged from 9,000 to 12,000. Thus, the native structure is likely a dimer (or larger aggregate) of identical subunits with the three disulfide bonds present occurring as intrachain links. Secondary structure predictions suggest a helical structure at the amino terminus. A comparison of the Er-1 amino acid sequence with known protein sequences did not reveal any significant similarities.
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PMID:Primary structure of the mating pheromone Er-1 of the ciliate Euplotes raikovi. 314 68

The amino acid sequence of the thioredoxin isolated from rabbit bone marrow was determined chiefly by high performance tandem mass spectrometry and fast atom bombardment mass spectrometry combined with manual Edman degradation. The sequences of peptides generated by digestion with trypsin alone or in combination with Staphylococcus aureus protease V8 or thermolysin were determined from their collision-induced dissociation mass spectra. Alignment of these sequences and additional sequence information were obtained from the collision-induced dissociation mass spectra of peptides obtained from digestion of the intact protein with S. aureus protease V8 and alpha-chymotrypsin. The resulting sequence of 104 residues is as follows: Val-Lys-Gln-Ile-Glu-Ser-Lys-Ser-Ala-Phe-Gln- Glu-Val-Leu-Asp-Ser-Ala-Gly-Asp-Lys-Leu-Val-Val- Val-Asp-Phe-Ser-Ala-Thr-Trp-Cys-Gly-Pro-Cys-Lys- Met-Ile-Lys-Pro-Phe-Phe-His-Ala-Leu-Ser-Glu-Lys- Phe-Asn-Asn-Val-Val-Phe-Ile-Glu-Val-Asp-Val-Asp- Asp-Cys-Lys-Asp-Ile-Ala-Ala-Glu-Cys-Glu-Val-Lys- Cys-Met-Pro-Thr-Phe-Gln-Phe-Phe-Lys-Lys- Gly-Gln-Lys-Val-Gly-Glu-Phe-Ser-Gly-Ala-Asn-Lys- Glu-Lys-Leu-Glu-Ala-Thr-Ile-Asn-Glu-Leu-Leu.
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PMID:Amino acid sequence of thioredoxin isolated from rabbit bone marrow determined by tandem mass spectrometry. 316 11


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