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)

Acidic proteins tend to be degraded more rapidly than neutral or basic proteins in rat liver, skeletal muscle, kidney and brain and in mouse liver and skeletal muscle. We now report a similar relationship among soluble proteins from rat lung, heart and testes, and from human fibroblasts and mouse-embryo cells grown in culture. These findings indicate that the correlation between protein net charge and degradative rate is a general characteristic of intracellular protein degradation in mammals. This relationship between isoelectric point and half-life appears to be distinct from the previously reported correlation between subunit molecular weight and protein half-lives. The more rapid degradation of acidic proteins does not result from their being of larger molecular weight than neutral or basic proteins. Furthermore, proteins within specific isoelectric point ranges still exhibit a relationship between subunit size and half-life. Finally, a group of membrane or organelle-associated proteins that are insoluble in phosphate-buffered saline and water but soluble in 1% Triton X-100 exhibit a correlation between size and half-life, but not between net charge and half-life. The biochemical reasons for the relationship between protein isoelectric point and half-life are unclear, although several possible explanations are presented. It is not due to a greater sensitivity of acidic proteins to proteolytic attack since experiments with a variety of endoproteinases, including trypsin, chymotrypsin, Pronase, papain, chymopapain, Staphylococcus aureus V8 proteinase, pepsin and lysosomal cathepsins from rat liver, have failed to demonstrate more rapid digestion of acidic proteins.
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PMID:Studies on the relationship between the degradative rates of proteins in vivo and their isoelectric points. 3 75

The antigenic relatedness of paracrystalline surface array proteins with subunit molecular weights of approximately 52,000 from isolates of Aeromonas hydrophila and Aeromonas veronii biotype sobria belonging to a single heat-stable serogroup was examined. Enzyme-linked immunosorbent assay and immunoblotting with two different polyclonal antisera against surface exposed and non-surface-exposed epitopes of the S-layer protein from A. hydrophila TF7 showed that the S-layer proteins of the mesophilic aeromonads were antigenically diverse. NH2-terminal amino acid sequence analysis of four antigenically different proteins showed that while the proteins were structurally related, they differed in primary sequence. Absorption experiments with heterologous live cells showed that cross-reactive epitopes were in non-surface-exposed regions of the S-layer proteins, while absorption with homologous live cells showed that the immunodominant epitopes of the S-layer protein of strain TF7 were strain specific and exposed on the surface of the native, tetragonal array produced by this strain. Proteolytic digestion of the TF7 S-layer protein with trypsin, chymotrypsin, or endoproteinase Glu-C produced an amino-terminal peptide of approximate Mr 38,000 which was refractile to further proteolytic cleavage under nondenaturing conditions. This peptide carried the immunodominant surface-exposed region of the protein, and chemical cleavage with cyanogen bromide further mapped the portion of these surface-exposed epitopes to a peptide of approximate Mr 26,000, part of which maps within the Mr 38,000 protease-resistant NH2-terminal peptide.
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PMID:Antigenic diversity of the S-layer proteins from pathogenic strains of Aeromonas hydrophila and Aeromonas veronii biotype sobria. 137 Feb 87

Insulin stimulated the tyrosine phosphorylation of a 61-kilodalton (kDa) protein in rat adipocytes prelabeled for 2 h with [32P]orthophosphate. Tyrosine phosphorylation of this 61-kDa protein displayed very similar insulin concentration dependency to receptor autophosphorylation and tyrosine phosphorylation of a high molecular mass receptor substrate of 160 kDa. Phosphorylation of the 61-kDa protein was very rapid with maximum labeling attained at 30 sec, paralleling that of the other two proteins. Phosphoamino acid analysis revealed that each of the insulin-responsive phosphoproteins contained phosphoserine as well as phosphotyrosine, though the ratio of two phosphoamino acids recovered from each protein differed. The 61-kDa protein yielded relatively equal proportions of phosphoserine and phosphotyrosine. In contrast, the insulin receptor yielded relatively more label on phosphotyrosine than phosphoserine, whereas label incorporated into the 160-kDa protein was recovered primarily on phosphoserine. Cleveland peptide maps using either Staphylococcus aureus V8 proteinase or chymotrypsin revealed no similarities between the 61-kDa protein and the other tyrosine phosphorylated proteins. With subcellular fractionation, the 160-kDa protein was found in equal proportions in the high speed pellet (100,000 g) and supernatant. The 61-kDa protein had a similar distribution to that of the 160-kDa protein but was also detected in the low speed pellet (10,000 g). The insulin receptor was localized to the low speed pellet. In summary, rat adipocytes contain an insulin-dependent phosphotyrosyl protein of 61 kDa which is distinct from the more prominent high molecular mass receptor substrate. This 61-kDa protein has characteristics consistent with it being a substrate for the insulin receptor tyrosine kinase.
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PMID:Insulin stimulates the tyrosine phosphorylation of a 61-kilodalton protein in rat adipocytes. 137 54

This study was undertaken in order to improve photoaffinity labelling efficiency of pancreatic cholecystokinin receptor by the cleavable probe 125I-ASD-(Thr28,Ahx31)-CCK-25-33 and to further characterize the denaturated receptor and its agonist binding domain. Membrane bound pancreatic cholecystokinin receptor was specifically labelled by 125I-ASD-(Thr28,Ahx31)-CCK-25-33 as a component of Mr approximately 85,000-100,000. The efficiency of the photolabelling was 3-4%. Performing photolysis on [125I-ASD-(Thr28,Ahx31)-CCK-25-33-receptor] complexes solubilized by CHAPS did not affect specificity of the labelling reaction but enhanced its efficiency so that up to 10% of the receptor site population could be cross-linked. Several lectins were tested for their ability to recognize and purify the cholecystokinin receptor denaturated by Nonidet P-40. Wheat germ agglutinin provided the best recovery and purification rate. The receptor was fully adsorbed on immobilized wheat germ agglutinin, while only a fraction was retained on ricin II (28%) and Ulex europaeus (58%), thus suggesting that the receptor is heterogeneously glycosylated. Finally, major labelled receptor fragments were generated by enzymatic digestion. There were: endoproteinase Glu-C----Mr approximately 34,000; endoproteinase Glu-C/trypsin----Mr approximately 12,000; chymotrypsin/endoproteinase Glu-C----Mr approximately 16,000 and 12,000. The fragment of Mr approximately 34,000 was deglycosylated to a component of Mr approximately 22,000 whereas the other fragments were insensitive to deglycosylation Such results strongly suggest that cholecystokinin binding occurs in a non-glycosylated domain of the cholecystokinin receptor protein.
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PMID:Biochemical characterization of a subtype pancreatic cholecystokinin receptor and of its agonist binding domain. 158 23

The connector of bacteriophage phi 29 is required for prohead assembly, binds DNA, and drives DNA packaging into viral proheads. Limited proteolysis of the connector protein with endoproteinase Glu-C from Staphylococcus aureus V8 and chymotrypsin showed that a domain of the NH2-terminal region is involved in DNA binding and in the subsequent packaging into preformed proheads, but not in prohead assembly. Mutants in specific amino acids of the NH2-terminal domain, obtained by directed mutagenesis techniques, showed that the Ala1-Arg2-Lys3-Arg4 region of the connector is absolutely necessary for DNA packaging into the proheads as well as for efficient DNA binding.
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PMID:Role of the amino-terminal domain of bacteriophage phi 29 connector in DNA binding and packaging. 158 68

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of S-layer proteins extracted from Campylobacter fetus strains by using acid glycine buffer showed that the predominant S-layer proteins of different strains had subunit molecular weights in the range of 90,000 to 140,000. Electron microscopy revealed oblique S-layer lattices with a spacing of approximately 5.6 nm (gamma = 75 degrees) on wild-type strains VC1, VC119, VC202, and VC203. Three variants of C. fetus VC119 producing a predominant S-layer subunit protein of different molecular weight (Mr) from that of the parent were also examined. Each variant produced an oblique lattice morphologically indistinguishable from that of the parent. Amino-terminal sequence analysis showed that the S-layer proteins of the VC119 parent and variants were identical up to residue 18 and that this sequence differed from but was related to the first 16 N-terminal residues shared by the S-layer proteins of the three other wild-type C. fetus isolates. Western immunoblot analysis with an antiserum prepared to the VC119 protein and an antiserum prepared to C. fetus 84-40 LP (Z. Pei, R. T. Ellison, R. V. Lewis, and M. J. Blaser, J. Biol. Chem. 263:6416-6420, 1988) showed that strains of C. fetus were capable of producing S-layer proteins with at least four different antigenic specificities. Immunoelectron microscopy with antiserum to the VC119 S-layer protein showed that C. fetus cultures contained cells with immunoreactive oblique S-layer lattices as well as cells with oblique S-layer lattices which did not bind antibody. This suggests that C. fetus S-layer proteins undergo antigenic variation. Thermal denaturation experiments indicated that the antigenicity conferred by the surface-exposed C. fetus S-layer epitopes was unusually resistant to heat, and the thermal stability appeared to be due to the highly organized lattice structure of the S. layer. Protease digestion of purified VC119 S-layer protein revealed a trypsin-, chymotrypsin-, and endoproteinase Glu-C-resistant domain with an apparent Mr of 110,000, which carried the majority of the epitopes of the S-layer protein, and a small enzyme-sensitive domain. The trypsin- and chymotrypsin-resistant polypeptides shared an overlapping sequence which differed from the N-terminal sequence of the intact S-layer protein.
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PMID:Antigenic differences among Campylobacter fetus S-layer proteins. 169 74

Rat alpha 1-inhibitor-3 is a 180-kDa monomeric proteinase inhibitor found in high concentration in rat plasma. By several criteria it has been shown to be a member of the family of alpha-macroglobulin proteinase inhibitors often exemplified by the tetrameric human alpha 2-macroglobulin. We have used limited proteolysis of rat alpha 1-inhibitor-3 to probe the domain structure of this family of proteins. Proteinases of different specificities, including trypsin, chymotrypsin, thermolysin, and Staphylococcus aureus V8 proteinase, were employed and a common fragmentation pattern was observed when the reaction products were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. These fragments were electrotransferred to polyvinylidene difluoride membranes and subjected to NH2-terminal amino acid sequence analysis in order to position them within the context of the primary structure. The fragmentation pattern may define the domain structure of alpha 1-inhibitor-3 and serve as a model for the domain organization of the family of alpha-macroglobulin proteinase inhibitors.
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PMID:Limited proteolysis of the alpha-macroglobulin rat alpha 1-inhibitor-3. Implications for a domain structure. 171 Feb 22

1. The riboflavin binding proteins from domestic fowl and Japanese quail have been isolated and their structures compared by circular dichroism, fluorescence and peptide mapping. 2. The two proteins have similar secondary structures, but differ in their tertiary structures as reflected in the environments of aromatic amino acid side chains. 3. Differences in amino acid sequence between the proteins are indicated by the digestion patterns obtained with thermolysin, chymotrypsin and V8 proteinase from Staphylococcus aureus. Both proteins are resistant to digestion by trypsin.
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PMID:A comparative study of the structure of egg-white riboflavin binding protein from the domestic fowl and Japanese quail. 175 22

The primary structure of the single-stranded DNA binding protein from Xenopus laevis oocyte mitochondria (mtSSB) has been determined by Edman degradation of the intact molecule and peptides derived from partial alpha-chymotrypsin proteolysis and enzymatic cleavage with trypsin and endoproteinase Glu-C. The native mtSSB is composed of two related polypeptide chains, mtSSBs and mtSSBr. The sequence of mtSSBs consists of 129 amino acids with a calculated molecular mass of 14,627 Da. Comparison of the first 80 residues of the two chains reveals 91% identity. A high degree of similarity is found between mtSSB and Escherichia coli SSB or F sex factor SSB.
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PMID:Primary structure of the two variants of Xenopus laevis mtSSB, a mitochondrial DNA binding protein. 195 53

Swarm rat chondrosarcoma contains a hyaluronan-binding protein of molecular mass 102 kDa (HABP102). The protein is present in 4 M-guanidinium chloride extracts of the chondrosarcoma and can be incorporated into reconstituted proteoglycan aggregates, but it is not present in native proteoglycan aggregates or in 0.5 M-guanidinium chloride extracts. HABP102 is unlikely to be an integral membrane protein, as it does not require detergent for extraction, is not enriched in hydrophobic amino acids and does not bind avidly to octyl-Sepharose. The protein stains poorly with Coomassie Blue and is only visible on PAGE gels after staining with silver. Disulphide bonds are essential for the binding of HABP102 to hyaluronan, and bivalent cations are not required for this interaction. HABP102 can be purified from dissociative chondrosarcoma extracts by sequential density-gradient centrifugation, hyaluronan-Sepharose affinity chromatography and hydrophobic-interaction chromatography. The amino acid composition is similar to that of domains 1-4 of the chondrosarcoma proteoglycan core protein, but peptide analysis after digestion with Staphylococcus aureus V8 proteinase and chymotrypsin and different immunoreactivity suggest that HABP102 is not closely related to proteoglycan hyaluronan-binding region. HABP102 is a glycoprotein containing N-acetylgalactosamine, N-acetylglucosamine, mannose and galactose.
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PMID:Purification and characterization of a hyaluronan-binding protein from rat chondrosarcoma. 231 94


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