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)

Purified avian myeloblastosis virus reverse transcriptase contains two subunits that are structurally related. The large subunit, beta (molecular weight, 95,000), was converted in vitro by chymotrypsin into a polypeptide of molecular weight 63,000. This polypeptide was indistinguishable from the small subunit, alpha (molecular weight, 65,000), in its chromatographic behavior on the phosphocellulose column and its tryptic peptide composition. During this proteolytic conversion, a polypeptide of molecular weight 32,000 (fragment B) was obtained. It was composed of tryptic peptides unique to beta and appeared to be derived from the portion of the beta subunit that was cleaved off during the conversion of beta into alpha. Upon continued proteolysis, a smaller polypeptide of molecular weight 24,000 (fragment A) was generated. This polypeptide manifested only RNase H activity and shared common amino acid sequences with beta and alpha subunits. Fragment A did not share any amino acid sequence homology with fragment B.
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PMID:Reverse transcriptase of RNA tumor viruses. V. In vitro proteolysis of reverse transcriptase from avian myeloblastosis virus and isolation of a polypeptide manifesting only RNase H activity. 7 71

Anhydrotrypsin, a derivative of bovine trypsin, immobilized on Sepharose tightly adsorbs various peptides containing L-arginine at the carboxyl termini, such as bradykinin and tuftsin. These peptides correspond to the specific products of the action of trypsin-like enzymes. Native trypsin immobilized on Sepharose does not show such strong affinity. Fragment 2, a peptide with 41 amino acid residues, which has been released together with bradykinin from bovine high-molecular-weight kininogen by the action of plasm kallikrein, is also adsorbed on the immobilized anhydrotrypsin. When only the carboxyl-terminal arginine is removed with carboxy-peptidase B, however, the peptide loses its adsorptive ability. Immobilized anhydrochymotrypsin, on the other hand, exerts specific affinity for the peptides which correspond to the products of chymotrypsin. These results suggest that the anhydro-derivatives of serine-proteseas in general may be of great use in the affinity chromatography of respective series of various naturally occurring peptides.
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PMID:Specific isolation of biologically-active peptides by means of immobilized anhydrotrypsin and anhydrochymotrypsin. 57 60

1. A trypsin and chymotrypsin inhibitor was isolated by extraction of chick-pea meal at pH8.3, followed by (NH4)2SO4 precipitation and successive column chromatography on CM-cellulose and calcium phosphate (hydroxyapatite). 2. The inhibitor was pure by polyacrylamide-gel and cellulose acetate electrophoresis and by isoelectric focusing in polyacrylamide gels. 3. The inhibitor had a molecular weight of approx. 10000 as determined by ultracentrifugation and by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. A molecular weight of 8300 was resolved from its amino acid composition. 4. The inhibitor formed complexes with trypsin and chymotrypsin at molar ratios of 1:1. 5. Limited proteolysis of the inhibitor with trypsin at pH3.75 resulted in hydrolysis of a single-Lys-X-bond and in consequent loss of 85% of the trypsin inhibitory activity and 60% of the chymotrypsin inhibitory activity. Limited proteolysis of the inhibitor with chymotrypsin at pH3.75 resulted in hydrolysis of a single-Tyr-X-bond and in consequent loss of 70% of the trypsin inhibitory activity and in complete loss of the chymotrypsin inhibitory activity. 6. Cleavage of the inhibitor with CNBr followed by pepsin and consequent separation of the products on a Bio Gel P-10 column, yielded two active fragments, A and B. Fragment A inhibited trypsin but not chymotrypsin, and fragment B inhibited chymotrypsin but not trypsin. The specific trypsin inhibitory activity, on a molar ratio, of fragment A was twice that of the native inhibitor, suggesting the unmasking of another trypsin inhibitory site as a result of the cleavage. On the other hand, the specific chymotrypsin inhibitory activity of fragment B was about one-half of that of the native inhibitor, indicating the occurrence of a possible conformational change.
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PMID:A trypsin and chymotrypsin inhibitor from chick peas (Cicer arietinum). 79 Dec 69

The amino acid sequences of two cyanogen bromide fragments from porcine pepsin have been determined. Fragment CB3 which represents the NH2-terminal 80 residues of pepsin was assembled from the peptides purified from proteolytic digests of this fragment using alpha-chymotrypsin, thermolysin, and staphylococcal protease. Two chymotryptic peptides were isolated from the NH2-terminal region of this fragment. One of these contains 2 extra residues, Ala-Leu-, at the NH2 terminus. This peptide is apparently derived from a different cleavage site of pepsinogen in its conversion to pepsin. The second cyanogen bromide fragment, CB4, contains 47 residues. The sequence was established from the peptides resulting from proteolytic digests using alpha-chymotrypsin, alpha-lytic protease, and thermolysin. An isoleucyl residue at position 29 of fragment CB4 appears to be absent in some molecules. This represents a structural variant of pepsin.
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PMID:Primary structure of porcine pepsin. II. Amino acid sequence of two cyanogen bromide fragments, CB3 and CB4. 109 37

In order to study the antigenic structure of histone H1(0) the purified protein from mouse liver was subjected to different chemical and enzymatic treatments (CNBr, acetic acid, trypsin, chymotrypsin). The resulting peptides were fractionated in SDS-containing or acid-urea polyacrylamide gels, transferred by electroblotting onto nitrocellulose paper and probed with specific rabbit anti-H1(0) antiserum. The C-terminal fragments 99-193 (obtained following acetic acid hydrolysis) and 107-193 (obtained by chymotrypsin digestion) also exhibited strong immunoreactivity. Fragment 1-30 (CNBr cleavage) contained antigenic determinants while the shorter fragments 1-22 and 1-28 (acetic acid hydrolysis) failed to show any detectable reactivity. It was concluded that, in contrast to histone H5 whose reactivity is mainly concentrated to the globular domain of the molecule, the antigenic determinants in histone H1(0) are more or less evenly distributed along the polypeptide chain with the possible exception of the short unstructured N-nose.
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PMID:Antigenic structure of histone H1(0). 172 85

Three forms of glucoamylase [EC 3.2.1.3] of a Rhizopus sp., Gluc1 (M.W. 74,000), Gluc2 (M.W. 58,600), and Gluc3 (M.W. 61,400), which have similar pH optima and specific activities towards soluble starch were studied as to their behavior towards raw starch. The pH optima for raw starch digestion were different, that is, 4.5 for Gluc1 and 5.0 for both Gluc2 and Gluc3. All the enzymes digested raw starch almost completely but at quite different rates; Gluc2 and Gluc3, which lack the N-terminal portions of Gluc1, were 22 and 25 times less effective, respectively, for raw starch digestion than Gluc1. Of the three enzymes, only Gluc1 tightly bound to raw starch. Binding of Gluc1 to raw starch occurred pH-dependently with a broad pH optimum of 4.5-5.5, but temperature and ionic strength affected it only slightly and little, respectively. The binding constant of Gluc1 for raw starch at pH 5.0 and 4 degrees C was estimated to be 1.2 X 10(5) M-1. Fragment H (M.W. 16,700), presumably released from the N-terminal part of Gluc1, not only bound to raw starch itself but also inhibited the binding of Gluc1 to raw starch. pap-Gluc (M.W. 57,000) and chymo-Gluc (M.W. 64,000), which are papain- and chymotrypsin-modified Gluc1, respectively, and lack the N-terminal portions of Gluc1, resembled Gluc2 and Gluc3 in raw starch binding as well as digestion. All these results indicate that Gluc1 has a raw starch-binding site, different from the active center, in the N-terminal region. Various substrates and analogs inhibited the binding of Gluc1 to raw starch, presumably due to steric hindrance.
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PMID:Different behavior towards raw starch of three forms of glucoamylase from a Rhizopus sp. 393 41

Mild chymotrypsin digestion of native lipase (449 amino acids) preferentially cleaved the Phe 335-Ala 336 bond. On SDS-gel electrophoresis, 3 major bands were observed: band 1 (52 kDa) representing native lipase, bands 2 and 3 (40 and 12 kDa) representing the two lipase fragments A and B. Fragment A does not retain lipase activity but maintains its ability to adsorb to interfaces. Fragment B was identified with the lipase C-terminal region (336-449). It does not exhibit any activity towards tributyrylglycerol emulsions and any ability to adsorb to interfaces.
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PMID:Limited proteolysis of porcine pancreatic lipase. Lability of the Phe 335-Ala 336 bond towards chymotrypsin. 397 56

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

The cyanogen bromide fragment CB67-129 of human prethrombin 1, corresponding to residues 54-116 of the thrombin B chain, is a potent chemotaxin for human peripheral blood monocytes and the murine macrophage like cell line, J774. Both of these cell types have been shown to respond chemotactically to alpha-thrombin and iPr2P-alpha-thrombin. Effective concentrations for stimulating directed cell movement with the fragment vary from 10(-11) to 10(-7) M. Moreover, CB67-129 and its parent protein compete for the same chemotactic receptor site. Fragment CB67-129, representing residues 54-116 of the human thrombin B chain sequence, contains a nine-residue insertion ("loop B") that is absent in homologous sequences derived from the closely related proteases chymotrypsin and trypsin. Unlike iPr2P-alpha-thrombin, iPr2P derivatives of these latter enzymes possess little or no chemotactic activity, suggesting a relationship between the insertion sequence and thrombin chemotactic activity. The loop B sequence is unique insofar as it contains all of the carbohydrate moieties known to reside in alpha-thrombin. However, chemotactic activity is only minimally reduced subsequent to hydrolysis by both neuraminidase and beta-galactosidase, indicating that receptor recognition and stimulated cell movement are mainly a function of structure of the cyanogen bromide derived fragment rather than of asparagine-linked carbohydrates.
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PMID:Localization of a chemotactic domain in human thrombin. 670 77

We have obtained a series of fragments growing from the N terminus of the protein chymotrypsin inhibitor-2 (C12) in order to study the development of structure on elongation of the polypeptide in solution. We present an extensive biophysical characterization of ten fragments using different conformational probes. Small fragments up to residue 40 of the 64-residue protein are disordered. Fragment (1-40) has non-native local hydrophobic clusters, but nevertheless does not bind 8-anilinonaphthalene-1-sulphonate (ANS). Hydrophobic regions in longer fragments become gradually more capable of binding ANS as the chain grows to completion, with a tendency to form native structures. Major changes in secondary structure and accessibility to hydrophobic sites occur in parallel, between (1-40) and (1-53), together with changes in hydrodynamic volume and flexibility. NMR studies of (1-53), the first fragment displaying tertiary interactions, show that a subcore is fully formed and the alpha-helix (residues 12 to 24) is of fluctuating structure. Fragments (1-53) and (1-60) share many properties with molten globule-like structures, with varying degrees or order. Fluorescence properties of the native fold are gradually recovered from fragments (1-60) to full-length C12, together with a decrease in hydrophobic exposure. A small degree of co-operativity of formation of structure appears when residue 60 is added, gradually increasing as residue 62 is added, but a full two-state co-operative transition appears only on addition of Arg62 and Val63. We believe this is the result of correct side-chain packing of the hydrophobic core, capping the major elements of secondary structure in C12 at this late stage, which is probed by the complete recovery of the fluorescence of the unique Trp5. The structures that develop as the polypeptide chain increases in length parallel the structural features present in the nucleus for the folding of intact protein, which develops in the transition state. The folding nucleus consists of much of the helix and the interactions made by Ala16 in the helix with residues in the core, especially with Leu49 and Ile57, with the rest of the structure being formed only very weakly in the transition state.
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PMID:Conformational pathway of the polypeptide chain of chymotrypsin inhibitor-2 growing from its N terminus in vitro. Parallels with the protein folding pathway. 750 Mar 64


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