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:3.4.21.1 (chymotrypsin)
10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Z discs were isolated from Lethocerus flight muscle by removing the contractile proteins from myofibrils with a solution of high ionic strength. The protein composition of the Z discs was analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis; the major proteins were alpha-actinin, actin and tropomyosin. Z lines were selectively removed from intact myofibrils by digestion with crude lipase and chymotrypsin, but not by purified lipase.
...
PMID:The proteins in the Z line of insect flight muscle. 84 68

Cleavage of caldesmon with chymotrypsin yields a series of fragments which bind both calmodulin and actin and inhibit the binding of myosin subfragments to actin and the subsequent stimulation of ATPase activity. Several of these fragments have been purified by cation exchange chromatography and their amino-terminal sequences determined. The smallest fragment has a molecular mass of about 7.3 kDa and extends from Leu597 to Phe665. This polypeptide inhibits the actin-activated ATPase of myosin S-1; this inhibition is augmented by smooth muscle tropomyosin and relieved by Ca(2+)-calmodulin. The binding of the 7.3-kDa fragment to actin is competitive with the binding of S-1 to actin. Thus, this polypeptide has several of the important features characteristic of intact caldesmon. However, although an intact caldesmon molecule covers between six and nine actin monomers, the 7.3-kDa fragment binds to actin in a 1:1 complex. Comparison of this fragment with others suggests that a small region of caldesmon is responsible for at least part of the interaction with both calmodulin and actin.
...
PMID:Localization and characterization of a 7.3-kDa region of caldesmon which reversibly inhibits actomyosin ATPase activity. 138 4

Previous studies have shown that the non-alpha-helical, amino-terminal head region of vimentin is essential for the formation and stability of vimentin intermediate filaments (IFs). In order to specify its target site on companion protein subunits, it was cut off from vimentin at amino acid position 96 with lysine-specific endoproteinase and allowed to react with intact vimentin and other IF proteins. In solution of high salt concentration (500 mM KCl), the isolated polypeptide (vim NT) showed a high affinity for all cytoplasmic IF proteins tested, but not for nuclear lamins. Employing limited digestion of the IF proteins with different proteinases, the binding site was shown to reside in their alpha-helical rod domains. Other polypeptides possessing alpha-helical regions with the potential to form coiled-coil structures like tropomyosin and myosin subfragment 2 did not react with vim NT. The binding to IF proteins was strongly inhibited by phosphorylation of vim NT and totally abolished in the presence of 200 mM arginine hydrochloride, whereas the same concentration of lysine hydrochloride was ineffective. Limited chymotryptic digestion of vim NT produced polypeptides that were unable to react with the alpha-helical region of vimentin at high salt concentration. Consistent with these observations, vim NT strongly inhibited filament formation in vitro from protofilamentous vimentin. A 14-mer oligopeptide comprising the amino acids 3 to 16 of the amino terminus also inhibited filament formation, though to a lesser extent. Conversely, vim NT and, with a lower efficiency, the 14-mer oligopeptide also severely affected the structure of preformed vimentin filaments by unraveling them. Phosphorylated vim NT was considerably less active in this respect. Further digestion of the rod domain of vimentin with chymotrypsin yielded 17.4 and 21 kDa polypeptides, which were tentatively characterized as originating from the carboxy- and amino-terminal half of the rod domain, respectively. Both formed salt-stable complexes with vim NT, the smaller polypeptide with a higher efficiency than the larger one. These results suggest that the staggered, antiparallel arrangement of the two coiled-coils in the protofilaments of IF proteins is, at least in part, determined by the twofold, symmetrical association of the amino-terminal head regions of one coiled-coil rope structure with the carboxy-terminal halves of the alpha-helical rod domains of the other coiled-coil and that similar interactions occur during filament assembly and in the intact filament.
...
PMID:Salt-stable interaction of the amino-terminal head region of vimentin with the alpha-helical rod domain of cytoplasmic intermediate filament proteins and its relevance to protofilament structure and filament formation and stability. 162 50

A monoclonal antibody (CG1) which recognizes tropomyosin isoforms 1 and 3 of chicken embryo fibroblasts was used to detect what is a motility-dependent change in the availability of the antigenic determinant in tropomyosin molecules along microfilaments. Immunofluorescence microscopy with this antibody revealed a heterogenous staining pattern among chicken embryo fibroblasts cells such that a population (17%) of cells showed only background staining. Stress fibers in about half the population of the cells stained weakly with this antibody, while the stress fibers in another population of cells (35%) showed very strong staining. After glycerination or cytochalasin B treatment, all of the cells became positive in reaction to CG1 antibody, suggesting that the antigenic determinant was present in every cell. On the other hand, all of the cells after brief nonionic detergent treatment became negative to CG1 antibody. The CG1 staining pattern was not significantly changed in cells at different stages after release from colcemid blockage, nor was a brief treatment of cells with buffer containing 2 M urea, mild trypsin, chymotrypsin, or V.8 protease effective in changing the reactivity. However, most of the cells with a morphology typical of movement, and all of the contracted, glycerinated cells were strongly positive to CG1 antibody. These results suggest that the unmasking of the CG1 determinant may be motility-dependent. Immunoblot analysis showed that forced modification on the cysteine residue of tropomyosin molecules, caused either by performic acid oxidation or by disulfide cross-linking with the chemical 5,5'-dithiobis (2-nitrobenzoate), results in drastic changes in the reactivity of the different isoforms to CG1 antibody. These results indicate that the cysteine residue is involved in the CG1 determinant. The motility-dependent unmasking of this determinant may suggest an important role for nonmuscle tropomyosin in regulating cell motility.
...
PMID:Motility-dependence of the heterogenous staining of culture cells by a monoclonal anti-tropomyosin antibody. 244 13

Limited digestion of caldesmon by alpha-chymotrypsin generates mainly 110, 80, 60, 38, and 28 kDa fragments. Affinity chromatography of these fragments on columns immobilized with myosin, HMM, or tropomyosin showed that the bound fraction from these columns was similar and it contained 110, 80, 60 and 28 kDa fragments. These fragments did not bind to myosin filaments, acto-HMM, actin or tropomyosin-actin in the solution, and they had no effect on the actin-activated ATPase of HMM. In contrast, the flow-through fraction from these affinity columns inhibited the actin-activated ATPase. Binding studies revealed that the 38 kDa fragment and its break down products bound to actin and tropomyosin-actin, and they were released partially from actin by calmodulin with a concomitant increase in the ATPase activity. These results indicate that, unlike the actin binding domain, the myosin and tropomyosin binding domains require the caldesmon molecule to be intact in order to exert their effects on the protein-protein interaction.
...
PMID:Characteristics of the myosin and tropomyosin binding regions of the smooth muscle caldesmon. 252 36

We have identified and isolated two new calcium-activated neutral hydrolases from human ventricular muscles. The one is an esterase, of which molecular weight was 300,000, required millimolar concentration of Ca2+, hydrolyzed Ac-Tyr-OEt X H2O, optiaml pH at 7.0. The other is an amidase, of which molecular weight was 70,000, also required millimolar concentration of Ca2+, hydrolyzed a synthetic substrate for chymotrypsin, Suc-Leu-Leu-Val-Tyr-MCA, with optimal pH at 7.2. Both enzymes did not degrade casein or contractile proteins (myosin, actin, troponin and tropomyosin). Their activities were not inhibited by exogenous protease inhibitors, leupeptin, antipain, monoiodoacetic acid and chymostatin, while the amidase activity was blocked by the endogenous inhibitor against calcium-activated neutral protease (CANP). Thus, their characters are different from chymotrypsin or CANP and they seems to be new hydrolases in the human heart.
...
PMID:Identification of two new calcium dependent hydrolases in the human heart. 301 Sep 97

Reaction between horse plasma gelsolin and fluorescein-5-isothiocyanate (FITC) resulted in incorporation of 4.8 +/- 0.6 fluorescein groups/gelsolin molecule. The sites of modification were not clustered in any one portion of the gelsolin polypeptide chain; all major peptides produced by proteolytic digestion with alpha-chymotrypsin exhibited a fluorescence characteristic of fluorescein. FITC-gelsolin has a peptide-backbone circular dichroism spectrum at 20 degrees C that is indistinguishable from that of native gelsolin, but FITC-gelsolin is considerably more resistant than native gelsolin to thermally induced precipitation. FITC-gelsolin is fully able to carry out severing of F-actin filaments, the prime function of gelsolin in plasma. An opening up of the structure of gelsolin on binding Ca2+ is evident from an increased susceptibility of FITC-gelsolin to quenching by I-. Ca2+ dependence of the interaction between gelsolin and actin is evident in titrations both of intensity and polarization of the fluorescence of FITC-gelsolin solutions. A Ca(2+)-sensitive interaction between gelsolin and tropomyosin also is observed.
...
PMID:Horse plasma gelsolin labelled with fluorescein isothiocyanate responds to calcium and actin. 838 9

Pen a 1, the major shrimp allergen from brown shrimp Penaeus aztecus has been identified as the muscle protein tropomyosin. To identify Pen a 1 IgE binding sites, the reactivities of Pen a 1-specific monoclonal antibodies (mAbs) and shrimp-allergic subjects' IgE to shrimp and homologous mammalian tropomyosins were analyzed. Pen a 1, purified by preparative SDS-PAGE and commercially obtained porcine, bovine and rabbit tropomyosin were cleaved by CNBr or digested by endoproteinases Lys-C, Glu-C, trypsin, Arg-C and chymotrypsin. Reactivities of Pen a 1-specific mAbs and IgE to the resulting peptides were analyzed by dot blot and immunoblotting. The dot blot analysis showed that mAbs and IgE antibodies did not react with any of the mammalian tropomyosins. The immunoblot analysis showed that all Pen a 1 digests bound IgE or mAbs. However, not all peptides in each digest possessed an IgE binding site. IgE binding intensity and frequency varied by subject and peptide digest. IgE and mAb reactivity patterns were similar but no mAb reproduced the IgE binding patterns indicating that subject' IgE bound some epitopes that were not recognized by the Pen a 1-specific mAbs. These studies suggest that IgE-binding epitopes are restricted to certain parts of the Pen a 1 molecule, Pen a 1 may have several similar epitopes, and that Pen a 1 epitopes do not appear to be located in the highly homologous parts of the tropomyosin molecule.
...
PMID:IgE and monoclonal antibody reactivities to the major shrimp allergen Pen a 1 (tropomyosin) and vertebrate tropomyosins. 909 46

We have isolated a full-length chitinase complementary DNA from the tiger shrimp Penaeus monodon that encodes a 621 amino acid protein possessing the functional domains of the chitinase protein family. The Penaeus monodon chitinase 1 (PmChi-1) gene product is 81.8% identical to a chitinase 1 protein expressed in the hepatopancreas of Penaeus japonicus. Analysis by reverse transcription-polymerase chain reaction (RT-PCR) indicates that PmChi-1 messenger RNA is detectable in the hepatopancreas and the gut. PmChi-1 expression during the molt cycle fluctuates markedly, with lowest mRNA levels at stages A(1), C, and D(3); there is a dramatic increase in transcript abundance at the D(2) stage. Using the same tissues and molt stages, RT-PCR analyses of genes encoding other digestive enzymes (trypsin, chymotrypsin, and cathepsin L), a muscle structural protein (tropomyosin II), and housekeeping proteins (elongation factor II and GTP-binding protein) indicate that PmChi-1 is expressed in a distinct tissue-specific and stage-specific manner. The other digestive enzyme genes are expressed in a similar spatiotemporal pattern, but none exhibited a dramatic increase in transcript abundance at stage D(2). Increased expression of PmChi-1 at D(2) suggests that hepatopancreas-expressed chitinase is involved in the degradation of endogenous chitin in the gut peritrophic membrane prior to molting.
...
PMID:The Penaeus monodon Chitinase 1 Gene Is Differentially Expressed in the Hepatopancreas During the Molt Cycle. 1081 51

Two isoforms of lobster muscle tropomyosin, a fast muscle type, fTm, and a slow muscle type, sTm1, are identical except for 15 residues within the region of amino acids 39-80, which corresponds to exon 2 of the tropomyosin genes of many phyla. Although the difference in the sequence does not include the terminal regions, the two isoforms are extremely different in viscosity, which is a good measure of the head-to-tail interaction strength and should be dependent on the conformation of the terminal 7-9 residues. To determine the influence of amino-acid replacements in the internal region on the overall conformation and the functional properties of the molecule, we compared the physical properties of the two isoforms and their interactions with other proteins, such as actin and myosin subfragment 1 (S1). Limited proteolysis by trypsin and chymotrypsin showed that sTm1 is more susceptible than fTm at the sites outside the region with the replaced residues. Compared with fTm, sTm1 showed higher viscosity, had a higher actin affinity, and inhibited acto-S1 ATPase to a greater extent. Finally, the binding isotherm of S1-ADP to actin-sTm1 is less sigmoidal than that to actin-fTm. These results indicate that the amino-acid replacements in the internal region alter the conformation and the physical properties of the entire molecule as well as its interactions with actin and myosin.
...
PMID:Amino-acid replacements in an internal region of tropomyosin alter the properties of the entire molecule. 1090 22


1 2 Next >>

---