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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete primary structure of a Streptomyces griseus (ATCC 13273) 7Fe ferredoxin, which can couple electron transfer between spinach ferredoxin reductase and S. griseus cytochrome P-450soy for NADPH-dependent substrate oxidation, has been determined by Edman degradation of the whole protein and peptides derived by Staphylococcus aureus V8 proteinase and trypsin digestion. The protein consists of 105 amino acids and has a calculated molecular weight, including seven irons and eight sulfurs, of 12,291. The ferredoxin sequence is highly homologous (73%) to that of the 7Fe ferredoxin from Mycobacterium smegmatis. The N-terminal half of the sequence, which is the Fe-S clusters binding domain, has more than 50% homology with other 7Fe ferredoxins. In particular, the seven cysteines known from the crystal structure of Azotobacter vinelandii ferredoxin I to be involved in binding the two Fe-S clusters are conserved.
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PMID:Primary structure of a 7Fe ferredoxin from Streptomyces griseus. 210 13

Acyl-CoA esters containing the photoreactive acids 12-(4'-azido-2'-nitrophenoxy)[1-14C]dodecanoic acid ([14C]AND-acid) or N-(4'-azido-2'-nitro-[3'-5'-3H]phenyl)-12-aminododecanoic acid ([3H]NANPA-acid) were synthesized. The photoreactive acyl-CoA esters could be bound to bovine acyl-CoA-binding protein (ACBP) and photocrosslinked to the protein. The photocrosslinked acyl-CoA-ACBP complex was separated from unlabelled ACBP on reverse-phase h.p.l.c. and the purified complex was digested with trypsin, Staphylococcus aureus V8 proteinase or endoproteinase Asp-N. By four independent peptide maps it was shown that the amino acids taking part in forming the hydrophobic binding site for acyl-CoA esters in bovine ACBP are located on the peptide segment from Asp21 to Asp38. Both photoreactive acyl-CoA esters used in this study labelled strongly in the segment from Tyr28 to Ala34. 12-(4'-Azido-2'-nitrophenoxy)[1-14C]-dodecanoyl-CoA ([14C]AND-CoA) also introduced a label at position Asp38, but o labelling was found before Ser29. In contrast, N-(4'-azido-2'-nitro[3',5'-3H]phenyl)-12-aminododecanoyl-CoA [3H]NANPA-CoA) also labelled the segment from Asp21 to Tyr28. The difference in labelling by the two photoreactive ligands is most likely caused by different mobility of the arylazido group when linked to the fatty acid either through a phenolic O- or an anilinic N- bond.
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PMID:Determination by photoaffinity labelling of the hydrophobic part of the binding site for acyl-CoA esters on acyl-CoA-binding protein from bovine liver. 222 14

1. The cytosolic aspartate aminotransferase was purified from human liver. 2. The isoenzyme contains four cysteine residues, only one of which reacts with 5,5'-dithiobis-(2-nitrobenzoic acid) in the absence of denaturing agents. 3. The amino acid sequence of the isoenzyme is reported, as determined from peptides produced by digestion with trypsin and with CNBr, and from sub-digestion of some of these peptides with Staphylococcus aureus V8 proteinase. 4. The isoenzyme shares 48% identity of amino acid sequence with the mitochondrial form from human heart. 5. Comparisons of the amino acid sequences of all known mammalian cytosolic aspartate aminotransferases and of the same set of mitochondrial isoenzymes are reported. The results indicate that the cytosolic isoenzymes have evolved at about 1.3 times the rate of the mitochondrial forms. 6. The time elapsed since the cytosolic and mitochondrial isoenzymes diverged from a common ancestral protein is estimated to be 860 x 10(6) years. 7. Experimental details and confirmatory data for the results presented here are given in a supplementary paper that has been deposited as a Supplementary Publication SUP 50158 (25 pages) at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1990) 265, 5.
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PMID:The amino acid sequence of cytosolic aspartate aminotransferase from human liver. 224 99

Human alpha 2-antiplasmin rapidly forms a stable, equimolar complex with either its target enzyme, plasmin, or with trypsin. Perturbation of the inhibitor-trypsin complex results in peptide bond cleavage at the reactive site of the inhibitor with the concomitant release of a small peptide fragment which apparently represents the carboxyl-terminal segment of the inhibitor. Sequence analysis of this fragment, together with that of an overlapping peptide obtained by treatment of native inhibitor with either Staphylococcus aureus V8 proteinase or human neutrophil elastase, yields data which indicate that the reactive site of alpha 2-antiplasmin encompasses a P1-P'1 Arg-Met sequence. However, unlike alpha 1-1-proteinase inhibitor which has a Met residue in the P1-position, oxidation of alpha 2-antiplasmin has no effect on its inhibitory activity toward either plasmin, trypsin, or chymotrypsin, indicating the lesser mechanistic importance of the P'1-residue during enzyme inactivation by this inhibitor.
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PMID:The reactive site of human alpha 2-antiplasmin. 243 12

A total of 16 hybrid myeloma clones secreting monoclonal antibodies (McAb) to rabbit or human serum low-density lipoprotein (LDL) were derived from the fusion of spleen cells from LOU or DA rats immunized with rabbit or human LDL and the rat myeloma lines Y3 Ag1.2.3 or YB2/0. Anti-(rabbit LDL) McAb showed limited reactivity with LDL from human, rhesus-monkey, rat and mouse serum. Six out of seven anti-(human LDL) McAb reacted with rhesus-monkey LDL, and only one showed partial cross-reaction with rabbit LDL. Binding-competition experiments indicated that the epitopes recognized by the anti-(rabbit LDL) IgG could be grouped into two major clusters: McAb in the first cluster reacted either with apo-(lipoprotein B-100) (apoB-100) and apo-(lipoprotein B-74) (apoB-74) or with apoB-100 but not with apo-(lipoprotein B-48) (apoB-48), the lower-Mr form of apoB of intestinal origin; the McAb in the second cluster all reacted with apoB-48 in addition to apoB-100 or apoB-100 and apoB-74. The six anti-(human LDL) IgG bound to separate epitopes on LDL. Further data on the epitope specificity of these McAb were obtained by antibody blotting after partial proteolysis of apoB-100 with trypsin or staphylococcal V8 proteinase, and the data confirmed the results obtained with the binding-competition experiments. One McAb to rabbit LDL inhibited the binding of LDL to the fibroblast LDL receptor (50% inhibition at a McAb/LDL molar ratio of 10). A similar result was produced by two other McAb at higher concentrations of antibody.
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PMID:Rat monoclonal antibodies to rabbit and human serum low-density lipoprotein. 245 11

A soluble form of the human CD4 glycoprotein (sCD4), the cellular receptor for human HIV, was treated with various physical, chemical, and enzymic regimens and tested over a range of concentrations for its capacity to inhibit the binding of HIV to CD4+ T cells. Reduction of disulfide bonds and alkylation in denaturing buffer (8 M urea) destroyed the inhibitory activity of sCD4, whereas reduction and alkylation in PBS had no effect. Derivatization or digestion of carbohydrate groups by periodate oxidation or by glycolytic enzyme digestion did not affect sCD4 inhibitory capacity. Digestion with trypsin or endoproteinase Glu-C destroyed activity. A limited digestion of sCD4 with endoproteinase Glu-C resulted in a mixture of fragments, however, and the mixture had inhibitory activity equivalent to that of intact sCD4. Within this mixture, a fragment of 23 kDa was identified that binds to HIV. Although sCD4 can be digested to yield fully active fragments, the requirement for intrachain disulfide bonding indicates that the minimum sized portion of CD4 that will retain full affinity for HIV will have to be formulated with a proper tertiary structure.
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PMID:Structural features of CD4 required for binding to HIV. 253 5

The three isozymic subunits of phosphofructo-1-kinase present in rabbit brain and designated A, B and C were phosphorylated in vitro by cyclic AMP-dependent protein kinase with 32P-labeled ATP. Limited digestion of the labeled enzymes with trypsin or with Staphylococcus aureus V8 proteinase led to the solubilization of radiolabeled peptides derived from the three isozymic subunits. Limited digestion by V8 proteinase was accompanied by a slight reduction in the apparent sizes of the subunits, indicating that the phosphorylated sites are located near either the amino or carboxyl termini of the protein. V8 proteinase digestion led to no change in the maximal activity of the enzyme but did abolish sensitivity to ATP inhibition. The phosphopeptides of the tryptic and the V8 digests were purified by chromatography and their amino acid sequences were determined and compared to the previously established sequence from rabbit muscle isozyme A. PFK-A E H I S R K R S G E A T V PFK-B H V T R R S L S M A K G F PFK-C V S A S P R G S Y R K F L In each instance, the phosphorylated serine, underlined in the above sequences, was found to be one or two residues toward the C-terminus of one or more basic residues. No other similarities in structure were noted.
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PMID:The sites of phosphorylation of rabbit brain phosphofructo-1-kinase by cyclic AMP-dependent protein kinase. 253 99

Rat fat cells contain three species of spontaneously active inhibitor proteins of protein phosphatase 1, as resolved by SDS-PAGE, with apparent molecular masses of 40 kDa, and 28 kDa respectively. The 33-kDa, thermostable inhibitor was highly purified from bovine adipose tissue and shown to be very similar to inhibitor-2 of skeletal muscle. It was phosphorylated, on threonine only, by glycogen synthase kinase 3. It formed an inactivated complex with protein phosphatase 1, that was reactivated by incubation with ATP-Mg and glycogen synthase kinase 3. By gel filtration it had a Stokes radius of 3.4 nm. Peptide and phosphopeptide maps, generated by Staphylococcus aureus V8 proteinase, trypsin or thermolysin, of the inhibitor and of the skeletal muscle inhibitor-2 were similar. The 40-kDa inhibitor, which was denatured by boiling, represents a novel protein phosphatase inhibitor protein or an undegraded precursor of inhibitor-2. The total activity of inhibitor-2-like material (thermostable and macromolecular) in an adipocyte cytosol extract corresponded to an intracellular concentration of 0.3 microM inhibitor-2.
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PMID:Adipose tissue protein phosphatase inhibitor-2. 282 48

Human apolipoprotein (apo) A-IV was purified from chylous ascites fluid. Proteolytic peptides produced by trypsin and Staphylococcus aureus V8 proteinase digestions were purified by high-performance liquid chromatography and sequenced. Human apoA-IV contains 376 amino acid residues. The peptide-derived sequence generally matches two previously reported DNA-derived amino acid sequences except for discrepancies in five positions. In order to examine these discrepancies further, one complete apoA-IV cDNA clone and another partial clone were sequenced. Comparison of all the available information indicates that the peptide-derived sequence reported here is accurate. Sequencing errors probably account for some of the discrepancies between the two primary sequences predicted by earlier nucleotide analyses. In certain positions, however, bona fide sequence heterogeneity or cloning artifact cannot be excluded.
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PMID:The primary structure of human apolipoprotein A-IV. 293 Jul 71

The primary structure of the Hypoderma lineatum collagenase was determined. Chymotrypsin digestion and thermolysin fragmentation of the chymotryptic core gave 30 and 5 peptides, respectively, accounting for all the residues of the protein. These peptides were aligned with overlapping peptides derived from tryptic and Staphylococcus aureus V8 proteinase digests. Hypoderma collagenase is a serine proteinase composed of 230 amino acids (Mr 25,223). It displays a high degree of sequential homology with the serine proteinases of the trypsin family, especially with another collagenolytic enzyme, the proteinase I of the crab Uca pugilator. The six half-cystinyl residues of Hypoderma collagenase correspond to 6 of the 10 half-cystinyl residues of chymotrypsin, and the residues forming the charge-relay system of the active site of chymotrypsin (His-57, Asp-102, and Ser-195) are found in corresponding regions. The prediction of the secondary structure of the collagenase is given.
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PMID:Complete amino acid sequence of the collagenase from the insect Hypoderma lineatum. 303 99


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