Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete primary structure of the coat protein of strain VRU of alfalfa mosaic virus (AMV) is reported. The strain is morphologically different from all other AMV strains as it contains large amounts of unusually long virus particles. This is caused by structural differences in the coat protein chain. The amino acid sequence has mainly been established by the characterization of peptides obtained after cleavage with cyanogen bromide and digestion with trypsin, chymotrypsin, thermolysin or Staphylococcus aureus protease. The major sequencing technique used was the dansyl-Edman procedure. The VRU coat protein consists of 219 amino acid residues corresponding to a molecular weight of 24056. Compared to the coat protein of strain 425 [Van Beynum et al. (1977) Eur. J. Biochem. 72, 63-78], 15 amino acid substitutions were localized. Most of them have a conservative character and may be explained by single-point mutations. A correction is given for the AMV 425 coat protein: Asn-216 was shown to be Asp-216. The prediction of the secondary structure for the two viral coat proteins was not significantly influenced by the various amino acid substitutions except for the region containing residues 65-100. This led us to the hypothesis that the AMV coat protein may occur in two different conformations favouring its incorporation into either a pentagonal or hexagonal quasi-equivalent position in the lattice of the protein shell. The substitutions in the above-mentioned region of the VRU coat protein may have caused a strong preference for the hexagonal lattice conformation. The model is supported by preliminary sequence data of the same coat protein region in AMV 15/64, a strain morphologically intermediate between 425 and VRU.
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PMID:The primary structure of the coat protein of alfalfa mosaic virus strain VRU. A hypothesis on the occurrence of two conformations in the assembly of the protein shell. 52 Mar 17

Partially purified flounder muscle (Pseudopleuronectus americanus) glyceraldehyde 3-phosphate dehydrogenase was immobilized on cyanogen bromide-activated Sepharose. The catalytic properties of the immobilized preparation were studied to determine if immobilization alters the kinetic properties of the native holoenzyme. The results indicate that the pH activity profile of immobilized glyceraldehyde 3-phosphate dehydrogenase did not differ from that of the native enzyme. The Michaelis constants (Km) for NAD and glyceraldehyde 3-phosphate were somewhat altered. The enzyme stability toward various inactivation treatments in the presence and absence of NAD was characterized and compared to that of he native enzyme. When either form of the enzyme was incubated with urea at concentrations greater than 2M, inactivation occurred very rapidly. Incubation in 0.1% trypsin for 60 minutes decreased the activity of immobilized glyceraldehyde 3-phosphate dehydrogenase by 45% and of the native soluble enzyme by 70%. The immobilized enzyme also exhibited considerably more stability than the native soluble enzyme when exposed to a temperature of 50 degrees or to 20 mM ATP. In all cases NAD either greatly reduced the rate of inactivation or completely protected the enzyme from inactivation.
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PMID:Immobilized flounder muscle glyceraldehyde 3-phosphate dehydrogenase. 56 63

The effects of trypsin inhibitors and phospholipase inhibitors on the acrosome reaction of washed cauda epididymal sperm of golden hamsters were studied using two different incubation systems. One incubation system, a non-synchronous acrosome reaction inducing system, included the use of a highly purified BSA and a protein-free motility factor preparation from hamster adrenal gland. The other system was a relatively synchronous acrosome reaction-inducing-system utilizing the calcium ionophore A23187. Acrosome reactions were inhibited by three low molecular weight synthetic trypsin inhibitors, benzamidine, NPGB and TLCK, when they were added five minutes prior to the initial occurrence of acrosome reactions in the non-synchronous system or five minutes prior to induction of acrosome reactions by A23187 in the synchronous system. Two phospholipase A inhibitors, p-bromophenacyl bromide and mepacrine, were also effective in inhibiting hamster sperm acrosome reactions in both incubation systems. TPCK, an inhibitor of several non-trypsin-like proteases, indomethacin, a prostaglandin synthetase inhibitor, and soybean trypsin inhibitor, a large molecular weight polypeptide, did not inhibit acrosome reactions. The inhibition of those acrosome reactions induced by A23187 provides further indirect evidence that the effective inhibitors were functioning at a site within the sperm. The overall results provide: (1) further support for our earlier work suggesting the involvement of an internal trypsin-like enzyme (presumably acrosin) rather than an exogenous trypsin-like enzyme in the hamster sperm acrosome reaction and (2) the first evidence suggesting the possibility that a sperm phospholipase may also be involved in the mammalian acrosome reaction.
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PMID:Further evidence in support of a role for hamster sperm hydrolytic enzymes in the acrosome reaction. 57 94

Human thyroglubulin labelled in vivo by 125I was purified from eight different thyroid glands including normal thyroid tissue, thyrotoxic goitre and euthyroid multinodular goitre. The purified protein was cleaved with cyanogen bromide (CNBr) and the resulting peptides were separated by column chromatography and ion exchange chromatography. Reproducible elution profiles of both protein and iodine were obtained. However, the distribution of iodine depended on the iodine content of the intact thyroglobulin. Small CNBr peptides seemed to be preferentially iodinated, but with a limited capacity. With higher degrees of iodination, larger peptides became richer in iodine. This suggests sequential iodination of the thyroglobulin molecule. The mixture of small peptides was digested by trypsin. Two iodopeptides were identified in this material by peptide mapping and they had identical migration in thyroglobulins of different origin. One of them was purified by ion exchange chromatography and high voltage electrophoresis. Analogous amino acid composition was obtained for the iodopeptide purified from two different thyroglobulins. The data indicates that thyroglobulin iodination occurs in specific portions of the polypeptide chain and probably in a sequential manner.
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PMID:Iodopeptides from human thyroglobulin. 57 57

The amino acid sequence of the beta-chain of the principal haemoglobin from the shark H. portusjacksoni has been determined. The chain has 141 residues, the same as that of mammalian alpha-chains and less than the 146 residues of mammalian beta-chains or the 148 residues of the alpha-chain from the tetrameric shark haemoglobin. The sequence was deduced from the sequences of peptides obtained by digestion of the globin or its cyanogen bromide fragments with trypsin, chymotrypsin, pepsin and papain. The difference in length of the beta-chain is most readily accounted for by the absence of the D helix. This small helical section is normally present in myoglobins and beta-globins but absent in alpha-chains. The deduction that it is absent from shark beta-chain is based on consideration of homology. The beta-chain shows the insertion of histidine beta2 and the deletions corresponding to residues A17 and AB1 relative to alpha-and myoglobin chains. The reactive thiol group in shark haemoglobin was shown by radioactive labelling to be residue 51 in the beta-chain, immediately preceding the E helix. The amino acid sequence of shark beta-chain shows 92 differences from human beta-chain, significantly more differences than shown by chicken or frog beta-chains, in line with its earlier time of divergence. If the tertiary structure of the shark beta-chain is the same as that of the horse then there are two changes in the alpha1beta2 contact site in oxyhaemoglobin and an additional one in deoxyhaemoglobin. When both alpha- and beta-chain contacts are considered there is a total of nine changes in residues involved in the alpha1beta2 contacts. There is no Bohr effect in shark haemoglobin, and of the residues normally involved in this effect the C-terminal histidine residue of the beta-chain is present, but the aspartyl (FG1) residue to which it is salt-linked is not, being replaced by a glutamyl residue.
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PMID:Haemoglobins of the shark, Heterodontus portusjacksoni. III. Amino acid sequence of the beta-chain. 61 4

The complete amino acid sequence of bovine phospholipase A2 (EC 3.1.1.4) was determined. This enzyme has a molecular weight of 13 782 and consists of a single polypeptide chain of 123 amino acids cross-linked by seven disulfide bridges. The main fragmentation of the polypeptide chain was accomplished by digesting the reduced and thialaminated derivative of the protein with trypsin, staphylococcal protease and cyanogen bromide. A number of chymotryptic peptides were used for alignment and to obtain overlaps of at least two residues. The sequence of the peptides was determined by Edman degradation by means of direct phenylthiohydantoin identification in combination with identification as dansyl amino acids. Although 71% of all residues of phospholipase A2 from bovine, porcine and equine sources are conserved, bovine phospholipase A2 differs from the others by the total number of residues and by substitutions at 20 (porcine) and 33 (equine) positions.
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PMID:The primary structure of bovine pancreatic phospholipase A2. 62 Jun 74

The major component of the casein fraction of human milk was cleaved by cyanogen bromide, and the composition of the resulting peptides was determined. Casein was also subjected to limited digestion by trypsin, and the amino acid composition of the isolated peptides was established. With this information the peptides were ordered as they occur in the purified protein.
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PMID:Isolation, composition and ordering of cyanogen bromide peptides in human casein. 62 58

Moloney leukemia virus activated both the classical and alternative pathways of human complement. About 500,000 virions were required to detect activation of the classical pathway whereas 5,000 times as many virions were necessary to initiate the alternative pathway, indicating that in this system only the former is of biological significance. Disruption of the virus with Triton X-100 destroyed its ability to initiate the alternative pathway without affecting its ability to activate the classical pathway. After ultracentrifugation of disrupted virus the active component could be recovered in the supernate and was isolated by isoelectric focusing in granulated gels. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic and analysis and cyanogen bromide digestion studies revealed that the activity resided in a methionine-containing protein having a pI of 7.5 and a molecular weight of approximately equal to 15,000 daltons. The purified protein interacts strongly with Clq and efficiently activates Cl. RNase and lipolytic enzymes had no effect on the isolated protein but incubation with trypsin resulted in loss of activity. Enzymatic digestion studies of surface-labeled virus indicate that the active protein is a viral membrane protein. On the basis of these results it is concluded that the complement receptor of Moloney leukemia virus is the surface protein p15E.
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PMID:Lysis of oncornaviruses by human serum. Isolation of the viral complement (C1) receptor and identification as p15E. 63 50

The complete amino acid sequence of the major component myoglobin from the pilot whale, Globicephala melaena, was determined by specific cleavage of the protein to obtain large peptides which are readily degraded by the automatic sequencer. The apomyoglobin was selectively cleaved at the two methionyl residues with cyanogen bromide and the acetimidated apomyoglobin was cleaved at the three arginyl residues by trypsin. From the sequence analysis of four of these peptides and the apoprotein, over 90% of the covalent structure of the protein was obtained. The remainder of the primary structure was determined by sequence analysis of three of the tryptic peptides isolated from the central cyanogen bromide fragment after modification of its single arginyl residue with 1,2-cyclohexanedione. This myoglobin differs from that of the Black Sea dolphin at four positions and from the myoglobin of the killer whale, Pacific common dolphin, and Atlantic bottlenosed dolphin at two positions. The above differences reflect the close taxonomic relationship of these five species of Cetacea. This sequence determination was aided by the use of a Texas Instruments 980A minicomputer system which performed peak integrations for all samples subjected to amino acid analysis.
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PMID:Complete amino acid sequence of myoglobin from the pilot whale, Globicephala melaena. 65 76

The C-terminal cyanogen bromide fragment of myoglobin from bottle nosed dolphin was digested with trypsin and two different derivatives of the digest were prepared, one being deuteroacetylated and deuteropermethylated, the other being submitted to one step of Edman degradation and then acetylated and permethylated. Comparison of the results obtained by computerized interpretation of the mass spectra of these two derivatives, combined with previous information about the sample, facilitated the sequence determination of all the peptides in the sample. Alignment of the peptides could then be carried out by homology with myoglobin from other cetaceans.
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PMID:Determination of the amino acid sequence of the C-terminal cyanogen bromide fragment of myoglobin from bottle nosed dolphin by mass spectrometric peptide mixture analysis. 65 60


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