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)

The biosynthesis in vivo of rat intestinal sucrase-isomaltase [a complex of sucrose alpha-glucohydrolase, EC 3.2.1.48, and oligo-1,6-glucosidase (dextrin 6-alpha-D-glucanohydrolase), EC 3.2.1.10] has been studied by following the incorporation of L-[6-(3)H]fucose into the enzyme with time. Immunoprecipitation of sucrase-isomaltase from Triton-X-100-solubilized Golgi or basolateral membranes and subsequent polyacrylamide gel electrophoresis revealed the presence of an immunoreactive glycoprotein with an apparent molecular weight approximately twice that of the separated sucrase-isomaltase subunits, but no active subunits were found in these membranes. This glycoprotein was also found in the microvillus membrane in addition to the subunits of sucrase-isomaltase. Kinetic studies showed a maximal labeling of this glycoprotein in Golgi membranes at 15 min, in basolateral membranes at 30 min, and in microvillus membranes at 45 min and a half-life of less than 30 min in each membrane. However, the radioactivity of the sucrase-isomaltase subunits in the microvillus membrane reached a plateau after 60 min. These data suggest that sucrase-isomaltase is synthesized as a one-chain polypeptide precursor that is split into the subunits after its transfer to the microvillus membrane. Elastase (EC 3.4.21.11), but not trypsin (EC 3.4.21.4) or alpha-chymotrypsin (EC 3.4.21.1), split the putative precursor into two polypeptides that had electrophoretic behaviors similar to those of the active enzyme subunits. These studies suggest that pancreatic proteases may play an important role in the late posttranslational processing of sucrase-isomaltase in vivo.
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PMID:Biogenesis of intestinal plasma membrane: posttranslational route and cleavage of sucrase-isomaltase. 29 33

Human platelets washed and fixed in paraformaldehyde aggregate in the presence of the antibiotic ristocetin and normal plasma. This aggregation response is abolished after digestion of the fixed platelets with chymotrypsin. Antisera to fixed washed platelets were produced in rabbits and absorbed with chymotrypsin-treated, fixed washed platelets. Monovalent Fab fragments obtained from the isolated gamma-globulin fractions of the antisera blocked ristocetin-induced aggregation of fixed washed platelets in buffer and normal platelets in platelet-rich plasma. By double-antibody immunoprecipitation, it was shown that the antibody which blocked the ristocetin reaction interacted with a platelet membrane surface protein of mol wt 155,000. The results suggest that the glycoprotein I complex on the surface of the human platelet mediates ristocetin-induced von Willebrand factor-dependent platelet aggregation.
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PMID:Immunoinhibition of ristocetin-induced platelet aggregation. 29 47

Chemical modifications of human plasma alpha1-antitrypsin with reagents which modify lysyl residues (citraconic anhydride, acetic anhydride, formaldehyde and 2,4,6-trinitrobenzenesulfonic acid) and arginyl residued (1,2-cyclohexanedione) were examined with regard to their effect upon the elastase inhibitory capacity of the glycoprotein. 2,4,6-Trinitrobenzenesulfonic acid was employed to quantitate the remaining free amino groups (epsilon-NH2 groups of lysine) and the extent of modifications. Amino acid analysis was utilized in the same capacity for the guanidino groups of arginyl residues. The elastase inhibitory capacity of alpha1-antitrypsin was destroyed following trinitrophenylation, citraconylation and acetylation. Circular dichroism of the native and modified derivatives revealed major changes in conformation following trinitrophenylation and citraconylation while CD profiles of acetylated and reductively methylated derivatives differed from that of the native profile considerably less. Reductively methylated alpha1-antitrypsin retained its elastatse inhibitory capacity. The reaction of 1,2-cyclohexanedione with alpha1-antitrypsin did not effect in a loss in inhibitory capacity. Gel filtration studies of native and modified alpha1-antitrypsin on Sephadex G-100 demonstrated an increased molecular weight presumably through molecular aggregation, in the citraconylated and trinitrophenylated derivatives, but not in the cases of the other derivatives. Based upon these studies and previous investigations of our laboratory, it was concluded that (1) alpha1-antitrypsin is a lysyl inhibitor type (i.e., the reactive site is a Lys-X bond), (2) its interaction with elastase follows a pattern similar to trypsin and chymotrypsin, and (3) the positively charged epsilon-NH2 group of lysine is essential for the maintenance of elastase inhibitory capacity.
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PMID:Circular dichroism of chemically modified human plasma alpha1-antitrypsin. Interaction with porcine elastase. 31 Mar 16

The receptors for aggregated immunoglobulin G (IgG) (an Fc receptor) and for ristocetin-von Willebrand factor on human platelets were studied by means of various modifications of the platelet surface. The expression of these receptors was measured by the agglutination of platelets to ristocetin in the presence of von Willebrand factor, which is part of the factor VIII complex, and by the binding of aggregated IgG coupled to 3H-labelled diazobenzene. Treatment of platelets with chymotrypsin, trypsin, papain and pronase which removed protein and glycoprotein from the platelet under conditions where the release reaction was inhibited caused loss of the expression of the receptor for ristocetin-von Willebrand factor and an enhancement of that for aggregated IgG. Induction of membrane changes with ADP and of the release reaction with the ionophore A23187 abolished agglutination to ristocentin-von Willebrand factor but did not alter the receptor for aggregated IgC. Possible contributions of unspecific membrane changes, produced by protease treatment of platelets, to the modification of receptor expression were eliminated by the use of formaldehyde-treated platelets. Trypsin, papain and pronase destroyed the ability of these platelets to agglutinate to ristocetin-von Willebrand factor but produced no change in the binding of aggregated IgC. Therefore, the receptor for ristocetin-von Willebrand factor is truly sensitive to proteolysis while the Fc receptor is not, but is partially masked by protease-sensitive material.
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PMID:A comparative study of the effect of modification of the surface of human platelets on the receptors for aggregated immunoglobulins and for ristocentin-von Willebrand factor. 31 30

Ovomucoid from the egg white of turtle-dove (Streptopelia risoria) was purified and shown to be a glycoprotein of mol. wt. 29 400, with valine as N-terminal residue. It is an inhibitor of both trypsin and chymotrypsin, but has a lower affinity for trypsin than has hen ovomucoid. Turtle-dove ovomucoid contains antigenic activity cross-reacting with the blood-group-P1 antigen of human erythrocytes. Hen ovomucoid has no detectable blood group-P1 activity. The carbohydrate composition of turtle-dove ovomucoid differs from hen ovomucoid in having substantially higher galactose content. The possible relationship between carbohydrate composition and antigenic activity is discussed.
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PMID:Turtle-dove ovomucoid, a glycoprotein proteinase inhibitor with P1-blood-group antigen activity. 43 57

In response to antigenic stimulation, the splenic lymphocytes from Toxoplasma-infected mice produce a factor which is called by the authors the Toxoplasma growth inhibitory factor (Toxo-GIF) and which inhibits the multiplication of Toxoplasma within nonimmune macrophages in vitro. In this study, partial characterization of murine Toxo-GIF was examined using Sephadex G-100 gel-filtration, isoelectric focusing, zonal electrophoresis and heat and enzymatic treatment. Peak activity of Toxo-GIF was found in a Sephadex G-100 fraction with a similar molecular size to that of the ovalbumin. The molecular weight of Toxo-GIF was calculated to be between 38,000 and 55,000. Toxo-GIF was stable to heating at 56 C for 30 min but lost its activity at 80 for 30 min or by exposure to pH values of 5 and 2. Exposure of Toxo-GIF to water-insoluble chymotrypsin or neuraminidase markedly decreased its ability to induce enhanced microbicidal activity of cultured macrophages, suggesting that Toxo-GIF was a glycoprotein. Furthermore, Toxo-GIF migrated in a region cathodal to mouse albumin on agar zone electrophoresis. Isoelectric focusing of active Sephadex fractions showed a well-defined peak of Toxo-GIF activity with an isoelectric point of pH 4.9 to 5.9.
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PMID:Some physicochemical characteristics of an immune lymphocyte product which inhibits the multiplication of toxoplasma within mouse macrophages. 44 Jan 44

EDCl is a novel glycoprotein, mol wt 27,000, isolated in 1976 from leukemic urine. It inhibits the serine proteases trypsin and chymotrypsin and is antigenically related to interalpha trypsin inhibitor (IATI), mol wt 170,000, a normal plasma antiprotease. Since psoriasis is a non neoplastic hyperproliferative state, we have now measured EDCl by a specific radioimmunoassay (RIA) in plasma and urine of 24 untreated psoriatic patients. EDCl was not detectable in normal urine (less than 1 mg/gm creatinine) or plasma (less than 1 mg/L). 55% of psoriatic urine specimens were positive by RIA, containing 8 to 110 mg/gm creatinine. 75% of plasmas were positive, containing 12 to 32 mg/L. Plasma and urine contents of EDCl were significantly (P less than .05) correlated with severity of clinical disease (% skin involved) but not with age, sex, distribution or type of lesion, family history or arthritis.
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PMID:Accumulation of urinary cancer-related glycoprotein, EDCl, in psoriasis. 47 29

The major red cell membrane protein, band 3, is a glycoprotein which extends across the membrane from the extracellular space into the cytoplasmic compartment. It is widely held that band 3 is a component of the intramembrane particles (IMP) which can be demonstrated by freeze-fracture electron microscopy. In this study, we find that the outer surface poles of the IMP can be seen by freeze-etching after they are unmasked by proteolysis under conditions which excise the surrounding sialopeptides from the membrane. The poles appear as distinctive projections, 30--50 A in diameter, the "ES particles." The ES particles remain associated with the outer surface of the membrane following cleavage of the band 3 polypeptide by chymotrypsin or pronase. This is consistent with previous biochemical studies which have shown that the 38,000-dalton outer surface segment of band 3 is intercalated in the lipid bilayer. A granulofibrillar component at the inner surface of the membrane is provisionally identified as the 40,000-dalton inner-surface domain of band 3.
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PMID:Fine structure of the band 3 protein in human red cell membranes: freeze-fracture studies. 72 68

Treatment of cattle red cells (CRC) with proteases and neuraminidase revealed at least one trypsin- or pronase-sensitive type and a protease-resistant type of sialoglycoprotein. The antigen F itself and the antigen IM in the F/F and F/V type of CRC were associated with the protease-resistant glycoprotein. Moreover, they were demonstrable in the agglutination test, but only after treatment with proteases. The antigen V, allelic to F, was, however, associated with a pronase-sensitive protein and the antigen IM in the V/V type of CRC with a trypsin- or pronase-sensitive glycoprotein. The antigen N' was inactivated by chymotrypsin or pronase, irrespective of whether it was transmitted with the F or with the V. While the antigens IM, N' and the antigen reacting with rabbit serum, in addition to the antigen F in the F/F type of CRC, showed no or only very weak (titre 1:2) reactions, these same antigens, in addition to the antigen V in the V/V type of CRC, all showed high titres (1:32 to 1:128) in the anti-globulin test.
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PMID:The effects of enzymes on the blood factors associated with the FV system of bovine erythrocytes. 73 Oct 67

Suspensions of oviduct cells were prepared by subjecting oviduct tissue to sequential incubations with EDTA, alpha-chymotrypsin, and crude collagenase, followed by a final incubation with EDTA. Cells isolated in this way incorporate mannose from exogenous GDP-mannose into mannosyl-lipid, oligosaccharide-lipid, and glycoprotein(s). Based on several criteria, the mannosyl-lipid is identical with mannosyl-phosphoryldolichol. Similarly, the oligosaccharide-lipid appears to be identical with the oligosaccharide-lipid synthesized in vitro (Lucas, J. J., Waechter, C. J., and Lennarz, W. J. (1975) J. Biol. Chem. 250, 1992-2002). In contrast, the glycoproteins are much lower in molecular weight than those labeled in cell-free preparations. Using intact oviduct cell suspensions it was found that: (a) exogenous GDP-mannose, not its breakdown products, serves as the direct mannosyl donor; (b) experiments using mixtures of known proportions of broken and intact cells, as well as studies with metabolic inhibitors, indicate that greater than 50% of the observed incorporation of mannose from GDP-mannose was catalyzed by enzymes associated with intact cells, rather than broken cells or membrane fragments; (c) incorporation of mannose from GDP-mannose into the mannosyl acceptors does not require energy and proceeds without significant uptake of GDP-mannose into trichloroacetic acid-soluble components of the cells; (d) under conditions where labeled guanosine incorporation into nucleic acids is readily detected, no incorporation of the guanosine moiety of [3H]GDP-mannose is observed. These results indicate that the enzymes catalyzing synthesis of lipid-linked intermediates involved in glycoprotein synthesis are not only associated with intracellular membranes, but with the plasma membrane as well.
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PMID:Utilization of exogenous GDP-mannose for the synthesis of mannose-containing lipids and glycoproteins by oviduct cells. 77 Apr 69


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