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

---

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

The structural polypeptides of two strains of measles virus grown in Vero cells were analysed in SDS-PAGE slab gels. Six major polypeptides were identified with mol. wt. of 79000, 72000, 60000, 43000, 40000 and 36000. The largest polypeptide was sensitive to trypsin digestion and was the dominant glycosylated polypeptide identified when the virus was grown in medium containing 3H-fucose or 3H-glucosamine or when the virus was treated with galactose oxidase and labelled with 3H-sodium borohydride. It is concluded that the 79000 mol. wt. polypeptide represents the haemagglutinin. Treatment with non-ionic detergent removed this polypeptide and also the 40000 mol. wt. polypeptide from the virus envelope. The 40000 mol. wt. polypeptide is probably associated with haemolysin and cell fusion activities and is analogous to the F1 of paramyxoviruses. A polypeptide of mol. wt. approx. 20000 detected after glycoprotein labelling may represent the F2 of measles virus. The 43000 mol. wt. polypeptide co-migrates with cellular actin and is the only major measles polypeptide that is heavily labelled when the virus is grown on Vero cells prelabelled with 35S-methionine. Thus it may represent cellular actin incorporated into the virus during maturation. The quantity of the 72000 mol. wt. polypeptide relative to the other major polypeptides varied considerably in different virus preparations. The role of the polypeptide could not be defined. By analogy with previously published data the 60000 and 36000 mol. wt. polypeptides are inferred to represent nucleocapsid and membrane proteins, respectively.
...
PMID:Structural polypeptides of measles virus. 65 Jan 74

Rabbit skeletal alpha-tropomyosin, separated by hydroxyapatite chromatography, was treated with trypsin (1/100 wt/wt) at 0 degrees C for 24 h. Trypsin-resistant fragments of tropomyosin were separated into the precipitate and supernatant fractions at pH 4.3 in 1 M KCl, and these were subjected to QAE-Sephadex A50 column chromatography for further purification. SDS-gel electrophoresis showed 16,000 and 14,000 dalton bands for the supernatant (s-fragment) and an 11,500 dalton band for the precipitate (p-fragment). We obtained a 13,500 dalton chain (13,500 dalton fragment) in addition to the s- and p-fragments upon treatment with more dilute trypsin (1/500 wt/wt) for 48 h at 0 degrees C. Both the p- and 13,500 dalton fragment had the same C-terminal portion as intact alpha-tropomyosin, and could form an intra-chain disulfide bond on oxidation. Therefore, these two fragments were deduced to be polypeptides from some points on the N-terminal side of Cys 190 to the intact C-terminal. The s-fragment, on the other hand, did not contain any cysteine, Phe, or His residues according to amino acid analysis, suggesting that the fragment is derived from the N-terminal side from Cys 190. Tentative assignment of the fragments was carried out by amino acid analysis, and C- and N-terminal determination. The p-, s-, and 13,500 dalton fragments appear to be in coiled-coil form in solution, having alpha-helical contents of 77,71, and 64%, respectively, and are able to interact with intact tropomyosin to reduce the viscosity of tropomyosin solution. The s-, p-, and 13,500 dalton fragments have little binding capacity individually to troponin, but the mixture, i.e., the s- and p-fragments, the 13,500 dalton fragment and the N-chain, which was obtained by cleavage at Cys 190, showed clear binding with troponin independent of Ca2+ in solution as detected by gel electrophoresis. The p-fragment showed some binding to troponin, since cross-linkage to troponin was possible by treatment with dimethyl suberimidate. From the result, it can be inferred that the troponin binding regions in tropomyosin are located on both sides of Cys 190, where trypsin attacks more easily than at other parts of the molecule, leaving two trypsin-resistant fragments.
...
PMID:Tropomyosin fragments obtained by tryptic digestion. 65 5

In contrast to other studies, our results demonstrate that low concentration of trypsin degrades a high proportion of proteolipid from CNS myelin. The Wolfgram protein and BP are vulnerable and completely lost on trypsinolysis, perhaps accounting for some of the peptides retained by the myelin. In PNS myelin, the major PO protein, a hydrophobic glycoprotein, is readily degraded to a stable 18,000--19,000 molecular weight unit, referred to as TPO protein, still retaining the carbohydrate unit which probably exists as a nonasaccharide grouping. Production of the TPO glycoprotein results from cleavage of a lysinyl-methionine or arginyl-methionine linkage probably found approximately 80--100 residues from the NH2-terminal isoleucine of the PO molecule. This linkage must be especially accessible to trypsin since the TPO protein is also generated in high yield when isolated PO protein is treated with trypsin in solution for 0.5 hours. Further incubation for 24 hours fully degrades the TPO protein to over 20 tryptic peptides, shown by peptide mapping, unlike the situation in myelin where the TPO unit is stable and resists further proteolysis. The TPO unit is also produced when PO protein is treated with BrCN. The PO protein contains 3 methionine residues but presumably the methionine residue in the trypsin-sensitive region is crucial; cleavage leads to the same TPO unit minus NH2-terminal methionine. Another methionine residue also exists in the TPO protein but it may be resistant to BrCN cleavage or else occupy a near-end position. Other proteins were also identified on PAGE of trypsinized PNS myelin: albumin, P2 protein, and PO protein. Albumin and P2 protein were identified in the acidic extract by reaction with specific antibody. The PO protein was isolated; it moved similarly to standard protein on SDS-PAGE and gave the appropriate amino acid analysis. However, it cannot be determined at this time whether a portion of these proteins remains because they are partially inaccessible to trypsin, or else are slightly attacked and thus represent early stages of trypsinolysis. The P2 protein of trypsinized myelin appears to migrate slightly faster than standard P2 protein on PAGE. Further work should clarify this point. Amino acid analysis and sequence data show that the PO protein is particularly hydrophobic, very likely existing in PNS myelin as an amphipathic molecule which penetrates the bilayer but which has a hydrophilic portion exposed. It is this hydrophilic region that contains much lysine, particularly the crucial lysinyl-methionine linkage, that is so trypsin-sensitive. Determination of the amino acid sequence of terminal portions of the isolated PO and TPO proteins serves to firmly establish the PO protein as a unique entity probably exclusive to PNS myelin. It can be concluded that the study of trypsin activity toward PNS myelin has made possible a new understanding of how proteins are positioned in the membrane, and provided valuable insight into the PO protein.
...
PMID:The action of trypsin on central and peripheral nerve myelin. 69 76

Cell walls were prepared from freeze-dried samples of 7 strains of Methanobacterium by mechanical disintegration of the cells followed by incubation with trypsin. Electron microscopy revealed the presence of sacculi exhibiting the shape of the original cells, on which no surface structure could be detected. Ultrathin sections of the isolated sacculi showed a homogenously electron dense layer of about 10--15 nm in width. The ash content varied between 8 and 18% of dry weight. The sacculi of all the strains contained Lys: Ala:Glu:GlcNAc or GalNAc in a molar ratio of about 1:1.2:2:1. In one strain (M. ruminantium M1) alanine is replaced by threonine, however, Neutral sugars and--in some strains--additional amounts of the amino sugars were present in variable amounts, and could be removed by formamide extraction or HF treatment without destroying the sacculi. No muramic acid or D-amino acids typical of peptidoglycan were found. Therefore, the sacculi of the methanobacteria consist of a different polymer containing a set of three L-amino acids and one N-acetylated amino sugar. From cells of Methanospirillum hungatii no sacculi, but tube-like sheaths could be isolated, which tend to fracture perpendicularly to the long axis of the sheath along the fibrills seen on the surface. The sheaths consist of protein containing 18 amino acids and small amounts of neutral sugars. They are resistent to the proteinases tested and are not disintegrated by boiling in 2% sodium dodecylsulfate for 30 min. The three Gram-negative strains Black Sea isolate JR-1, Cariaco isolate JR-1 and Methanobacterium mobile do not contain a rigid sacculus, but merely a SDS-sensitive surface layer composed of regularly arranged protein subunits. This evidence indicates that, within the methanogens, different cell wall polymers characteristic of particular groups of organisms may have evolved during evolution, and supports the hypothesis that the evolution of the methanogens was separated from that of the peptidoglycan-containing procaryotic organisms at a very early stage.
...
PMID:Chemical composition of the peptidoglycan-free cell walls of methanogenic bacteria. 69 4

The conditions of digestion of colicin E3 with trypsin were examined to obtain an active fragment (T2A) of colicin E3, and a method suitable for large-scale preparation of T2A was developed. The T2A preparation thus obtained was homogeneous on SDS-polyacrylamide gel electrophoresis and the molecular weight was estimated to be about 11,000. T2A was composed of 97 amino acid residues and was rich in basic amino acids; methionine, valine, cysteine, and cystine were absent. The N-terminal residue was lysine and the structure near the C-terminus was -Lys-Lys-Tyr-Leu. Since T2A had no lysine or arginine residue at the C-terminus and since the C-terminal structure was identical to that of protein A, it was concluded that T2A was derived from the C-terminal region of protein A. No clear differences were detected among T2A preparations obtained from 3 different fractions of colicin E3, suggesting that the apparent homogeneity of colicin E3 does not involve the T2A region.
...
PMID:Preparation and characterization of an active fragment of colicin E3. 73 Jul 46

1) S. mutans strains of serotypes a, d and g were strongly agglutinated with soluble glucans and dextran T2000. Homologous glucan did not in all cases produce agglutination. 2) The quantity of low molecular weight dextrans bound (T20 and T70) does not correspond to the agglutination induced by glucan or T2000. 3) The agglutination and binding of high molecular weight glucan by B13 cells was sensitive to heat, trypsin, dextranase, EDTA, SDS and urea, whereas no inhibition of binding of T20 and T70 was seen. 4) Pretreatment of B13 cells with anti-d, or anti-glucan sera, or Con A, RCA I, or RCA II completely inhibited agglutination by T2000 and caused a significant reduction of the binding of glucan. No reduction in the binding of T20 and T70 occurred. 5) An agglutination-negative mutant was agglutinated by sucrose but not by T2000 or high molecular weight glucan. It bound normal levels of T20 and T70. 6) The results indicate that B13 cells possess multiple glucan binding sites and that the site responsible for agglutination consists of both polysaccharide and protein. 7) Inhibition studies on agglutination and adherence using B13 cells indicate that the two processes involve different mechanisms.
...
PMID:Dextran/glucan binding by Streptococcus mutans: the role of molecular size and binding site in agglutination. 74 9

Native spectrin has trypsin-susceptible sites spaced at a constant molecular weight interval. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of spectrin treated with trypsin at low salt concentrations shows a ladder of fragments spaced at approximately 8,000-dalton intervals, from the intact Band 1 (240,000 daltons) and Band 2 (220,000 daltons) down to about 150,000 daltons. The five largest fragments were identified as products of Band 2 using tryptic 125I-peptide mapping of protein from gel slices. Endogenously incorporated [32P]phosphate is absent from the largest fragment, indicating that all phosphorylation sites on spectrin are within 8,000 daltons of a terminal of Band 2. Mapping of both [14C]carboxyamidomethylated cysteine-containing tryptic peptides and 125I-peptides reveals extensive sequence homology between the spectrin subunits. Further, only somewhat over half of the distinct spots expected from the cysteine content are found in both Band 1 and Band 2 peptides. These and the tryptic susceptibility results are interpretable as evidence for a repeating structure in spectrin.
...
PMID:Structural studies on human spectrin. Comparison of subunits and fragmentation of native spectrin. 76 4

A partially purified enterotoxin was obtained from the growth medium of Escherichia coli strain 711 (P307), a derivative of E. coli K-12, by ultrafiltration, precipitation with ammonium sulfate, molecular sieving, and anion exchange column chromatography. The active moiety, which is heat-labile, behaved like a protein particle of 180,000 to 200,000 daltons during molecular sieving and ultracentrifugation. During polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS-PAGE), it dissociated into two subunits with apparent molecular weights of 68,000 to 70,000 and 14,000 to 15,000. SDS-PAGE after heating in SDS changed the larger subunit to an apparent molecular weight of about 40,000; the smaller subunit did not change. The intact particle induced rounding of the cells in Y-1 mouse adrenal tumor cells used for assay. The detergent-dissociated molecules were not active. Proteolysis of the purified toxin by tolylsulfonyl phenylalanyl chloromethyl ketone-trypsin appeared to enhance its activity. The addition of serum to the assay medium resulted in partial depression of the activity. Activity was also abolished by preincubation of the toxin with either a rabbit antiserum to it or solutions containing GM1 ganglioside. The length of time needed to evoke a response in the assay system by fractions from different stages in the purification of the enterotoxin was a useful parameter in the evaluation of specific activity.
...
PMID:Partial purification and characterization of a heat-labile enterotoxin of Escherichia coli. 78 81

Platelet factor 4 (PF4, a heparin-neutralizing protein) was isolated from washed human platelets. It was found to be homogenous by SDS-polyacrylamide gel electrophoresis, immunodiffusion, and immunoelectrophoresis, when tested with monospecific antibody produced in rabbits. PF4 is a heat-stable protein, but its antiheparin activity and antigenicity are destroyed by trypsin. The molecular weight of PF4 as calculated by amino acid analysis is approximately 8000 and by SDS-polyacrylamide gel electrophoresis with beta-mercaptoethanol, 7100 daltons. PF4 migrated to the cathode at pH 8.6. The interaction of PF4 with heparin resulted in the formation of a complex which migrated to the anode, as tested by immunoelectrophoresis. Incubation of purified PF4 with its antibody at 37 degrees C resulted in a loss of antiheparin activity. The presence of antiheparin activity and of PG4 antigen in material released during platelet aggregation by various agents and at various stages of the preparative procedure closely correlated. It has been concluded that PF4 antigen and antiheparin activity are two properties of the same protein. Comparison of human and pig PF4 revealed significant biochemical and antigenic differences.
...
PMID:Antigenic and antiheparin properties of human platelet factor 4 (PF4). 80 47

The orientation of human erythrocyte membrane protein was examined by enzymic iodination using lactoperoxidase with the glucose-oxidase system for generating peroxide, followed by proteolytic digestion. The outer surface of intact cells was labeled with 125I and the cytoplasmic surface of either resealed ghosts containing lactoperoxidase or of inside-out vesicles was labeled with 131I. Following iodination, the outer surface (resealed ghosts) or the cytoplasmic surface (outer surface of inside-out vesicles) was digested with trypsin, chymotrypsin, or pronase. Sodium dodecyl sulfate gel electrophoresis of the isolated membranes revealed three major and several minor peaks of radioactivity. Their surface orientation, defined within the limits of the specificity of the probes used, was as follows: the three major peaks consist of: (a) a 90,000 to 100,000 molecular weight component labeled on both surfaces; its proteolytic digestion profile indicated that it spans the membrane in an asymmetric manner and that it is composed of more than one peptide; (b) the major red cell membrane glycoprotein (apparent molecular weight 60,000) which is labeled and digested at only the outer surface; and (c) peptide(s) of high molecular weight (approximately 200,000), labeled and digested at only the cytoplasmic surface. The minor components include a glycoprotein of approximately 25,000 (apparent molecular weight) accessible to both surfaces and peptides of 60,000 to 70,000, 45,000, and 20,000 molecular weight labeled only on the inner surface.
...
PMID:Arrangement of human erythrocyte membrane proteins. 80 40


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---