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)

Acetobacter aceti produces two different terminal oxidases dependent on the culture conditions, shaking and static cultures. Cells grown on shaking culture contain cytochrome a1, while cytochrome o is present in cells grown on static culture. Cytochrome a1 and cytochrome o of A. aceti were compared especially with respect to the protein structure and the prosthetic groups. Cytochrome a1 exhibited lower CN sensitivity and higher affinity for O2 than cytochrome o. Both terminal oxidases consisted of four nonidentical polypeptides of which the molecular sizes were identical between both enzymes. Cytochrome a1 cross-reacted with an antibody raised against cytochrome o at the same level as cytochrome o did, and an antibody elicited against cytochrome a1 cross-reacted with both cytochrome o and cytochrome a1 at the same intensity, which indicates that both oxidases are indistinguishable immunochemically. Furthermore, almost the same peptide mapping pattern with chymotrypsin was observed in subunit I and in subunit II between both terminal oxidases, and the amino-terminal sequences in the subunit II of both oxidases were identical at least in their 10 amino acids. As for the prosthetic groups, both oxidases were shown to contain two heme-irons and one copper atom. Further, high performance liquid chromatography analysis of the heme moieties extracted from both the purified enzymes indicated that cytochrome a1 contains hemes b and a at a ratio of 1 to 1, whereas cytochrome o contains the same amounts of hemes b and o. Thus, data indicate that cytochrome a1 and cytochrome o of A. aceti are cytochrome ba and cytochrome bo ubiquinol oxidases, respectively, and that both oxidases have a closely similar protein structure and prosthetic groups, in which only heme a in the heme/copper binuclear center of cytochrome a1 is replaced by heme o in that of cytochrome o.
...
PMID:Homology in the structure and the prosthetic groups between two different terminal ubiquinol oxidases, cytochrome a1 and cytochrome o, of Acetobacter aceti. 133 65

gamma-Radiolysis, with doses less than 1 kGy, of aqueous solutions of disulphides, disulphide-proteins or thiols leads to the generation of stable products, capable of stimulating the catalytic reduction of Fe(III)-cytochrome-c by unirradiated glutathione, and by other thiols. The stimulatory activity fades within 20-60 min in the case of irradiated thiols, but there was little loss of this activity when irradiated solutions of disulphides or disulphide-proteins were stored at 4 degrees C for days. Disulphides (e.g. cystamine) are mainly activated by .OH radicals, disulphide-proteins (e.g. alpha-chymotrypsin) mainly by e-aq, and thiols (e.g. cysteine) by virtually all water radicals. The radiolytic activation, which is only partially prevented by oxygen, can be attributed to the generation of trace amounts of higher sulphides and persulphides (RSSSR, RSSSSR and RSSH). Such species are known to stimulate Fe(III)-cytochrome-c reduction by glutathione in a chain reaction (Massey et al. 1971). The radiolytic stimulation of reductive catalytic activity of thiols and disulphides may play a role in irradiated biological systems, and might be exploited to identify irradiated proteins with Fe(III)-cytochrome-c as detector.
...
PMID:Catalytic reduction of Fe(III)-cytochrome-c involving stable radiolysis products derived from disulphides, proteins and thiols. 134 23

In a recent study [Wang & Beattie (1991) Arch. Biochem. Biophys. 291, 363-370], we reported that dicyclohexylcarbodiimide (DCCD) inhibited proton translocation in the cytochrome bf complex reconstituted into proteoliposomes and was bound selectively to cytochrome b6. To establish the site of binding of DCCD on cytochrome b6, the cytochrome bf complex labeled with [14C]DCCD was selectively digested with chymotrypsin and trypsin. A 17-kDa fragment containing radioactive DCCD and the heme moiety was obtained after chymotrypsin digestion, while a 12.5-kDa fragment containing both radioactive DCCD and the heme moiety was obtained after trypsin digestion, suggesting that the site of DCCD binding might be on aspartate-140, aspartate-155, or glutamate-166. Extensive digestion of cytochrome b6 isolated from a [14C]DCCD-labeled cytochrome bf complex with trypsin followed by isolation and sequencing of two radioactive peptides obtained revealed that DCCD is bound at either residue aspartate-155 or residue glutamate-166 localized in amphipathic extramembranous helix IV. In addition, the cytochrome bf complex labeled with [14C]DCCD was reconstituted into liposomes and digested with trypsin. Three fragments of 9.3, 10.5, and 11.5 kDa were obtained, suggesting that the four-helix model for the topography of cytochrome b6 in the membrane is correct.
...
PMID:Binding of dicyclohexylcarbodiimide to aspartate-155 or glutamate-166 of cytochrome b6 in a cytochrome bf complex isolated from spinach thylakoids. 139 Jun 29

Structural studies carried out on a cross-linked complex between cytochrome c3 and ferredoxin I, both isolated from Desulfovibrio desulfuricans Norway, allowed the identification of the site of interaction between the two redox proteins. Staphylococcus aureus proteinase and chymotrypsin digestions led to characterization of peptides containing both cytochrome c3 and ferredoxin sequences. The cytochrome c3 sequences involved in the three isolated cross-linked peptides contained several lysine residues localized around the heme 4 crevice. This analysis stressed the peculiar role of lysines 100, 101, 103, 104 and 113, which could be considered as major cross-link sites, as opposed to the lysines 75, 79 and 82, which could be considered as minor cross-link sites. One cross-linked peptide, containing two ferredoxin sequences joined to one cytochrome c3 sequence, had been isolated, suggesting the possibility of more than one cross-link per covalent complex. All these results led to the identification of heme 4 of cytochrome c3 as the site of interaction for the ferredoxin I. This study confirms the proposal that could be deduced from the hypothetical structure of the complex built by computer graphics modelling (Cambillau, C., Frey, M., Mosse, J., Guerlesquin, F. and Bruschi, M. (1988) Proteins: struct., funct. genet. 4, 63-70).
...
PMID:Identification of the site of interaction between cytochrome c3 and ferredoxin using peptide mapping of the cross-linked complex. 164 31

The cytochrome d complex is a two-subunit, membrane-bound terminal oxidase in the aerobic respiratory chain of Escherichia coli. The enzyme catalyzes the two-electron oxidation of ubiquinol and the four-electron reduction of oxygen to water. Previous work demonstrated that the site for ubiquinol oxidation was selectively inactivated by limited proteolysis by trypsin, which cleaves at a locus within subunit I. This work is extended to show that a similar phenomenon is observed with limited chymotrypsin proteolysis of the complex. The cleavage patterns are similar whether one uses the purified oxidase in nondenaturing detergent or reconstituted in proteoliposomes or uses spheroplasts of E. coli as the substrate for the proteolysis. Hence, the protease-sensitive locus is periplasmic in the cell. Fragments resulting from proteolysis were characterized by N-terminal sequencing and by immunoblotting with the use of a monoclonal antibody of known epitope within subunit I. The data indicate that inactivation of the ubiquinol oxidase activity results from cleavage at specific residues with a hydrophilic region previously defined as the Q loop. This domain has been already implicated in ubiquinol oxidation by the use of inhibitory monoclonal antibodies. Electrochemical and HPLC analysis of the protease-cleaved oxidase suggests no global changes in either the quaternary or tertiary structure of the enzyme. It is likely that the Q loop is directly involved in forming a portion of the ubiquinol binding site near the periplasmic surface of the membrane.
...
PMID:Proteolysis of the cytochrome d complex with trypsin and chymotrypsin localizes a quinol oxidase domain. 170 10

The expression of cytochrome c3 from Desulfovibrio vulgaris (Hildenborough) was examined in Escherichia coli transformed with either of two plasmids, pJ8 and pJ81. The former has an 840 bp insert of D. vulgaris DNA, containing the structural gene for cytochrome c3 (387 bp) and its promoter region. Plasmid pJ81 was generated from pJ8 by deoxyoligonucleotide-directed mutagenesis to direct the synthesis of a protein with an altered signal peptidase cleavage site [Ala(-1)----Asp(-1)]. Synthesis of the 14 kDa precursor, which was partly processed to the 12 kDa mature protein, was observed in cells of E. coli TG2(pJ8) by SDS gel electrophoresis and Western blotting. Analysis of spheroplasts revealed that the processed polypeptide was present in the periplasm while the precursor was found only in the membrane/cytoplasmic fraction. No processing was observed in E. coli TG2(pJ81) cells, due to the mutation of the signal peptide cleavage site. No insertion of haem into the E. coli product could be detected in E. coli TG2(pJ8) cells by post-electrophoretic protohaem fluorescence analysis. The sensitivity of the cytochrome c3 synthesized in E. coli TG2(pJ8) to digestion by chymotrypsin also indicated that the apoprotein was formed. The results indicate that E. coli is capable of synthesizing and exporting the cytochrome c3 polypeptide, but fails to insert the haems.
...
PMID:Expression of the gene encoding cytochrome c3 from Desulfovibrio vulgaris (Hildenborough) in Escherichia coli: export and processing of the apoprotein. 256 Dec 88

Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.
...
PMID:Sodium-calcium exchange in sarcolemmal vesicles from tracheal smooth muscle. 282 16

The reagent 1-ethyl-3-(3-[14C]trimethylaminopropyl)carbodiimide (ETC) was used to identify specific carboxyl groups on the cytochrome bc1 complex (ubiquinol-cytochrome c reductase, EC 1.10.2.2) involved in binding cytochrome c. Treatment of the cytochrome bc1 complex with 2 mM ETC led to inhibition of the electron transfer activity with cytochrome c. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that both the cytochrome c1 heme peptide and the Mr = 9175 "hinge" peptide were radiolabeled by ETC. In addition, a new band appeared at a position consistent with a 1:1 cross-linked cytochrome c1-hinge peptide species. Treatment of a 1:1 cytochrome bc1-cytochrome c complex with ETC led to the same inhibition of electron transfer activity observed with the uncomplexed cytochrome bc1, but to decreased radiolabeling of the cytochrome c1 heme peptide. Two new cross-linked species corresponding to cytochrome c-hinge peptide and cytochrome c-cytochrome c1 were formed in place of the cytochrome c1-hinge peptide species. In order to identify the specific carboxyl groups labeled by ETC, a purified cytochrome c1 preparation containing both the heme peptide and the hinge peptide was dimethylated at all the lysines to prevent internal cross-linking. The methylated cytochrome c1 preparation was treated with ETC and digested with trypsin and chymotrypsin, and the resulting peptides were separated by high pressure liquid chromatography. ETC was found to label the cytochrome c1 peptides 63-81, 121-128, and 153-179 and the hinge peptides 1-17 and 48-65. All of these peptides are highly acidic and contain one or more regions of adjacent carboxyl groups. The only peptide consistently protected from labeling by cytochrome c binding was 63-81, demonstrating that the carboxyl groups at residues 66, 67, 76, and 77 are involved in binding cytochrome c. These residues are relatively close to the heme-binding cysteine residues 37 and 40 and indicate a possible site for electron transfer from cytochrome c1 to cytochrome c.
...
PMID:Identification of the binding site on cytochrome c1 for cytochrome c. 298 91

A cytochrome P-450 (P-450SG1) was purified from a lanosterol 14 alpha-demethylase (P-450(14DM)) defective mutant of Saccharomyces cerevisiae, strain SG1, by a method similar to that used in the purification of the wild type enzyme (Yoshida, Y., and Aoyama, Y. (1984) J. Biol. Chem. 259, 1655-1660). P-450SG1 had the same apparent Mr as and was immunochemically identical to P-450(14DM). Peptide maps of P-450SG1 made by limited proteolysis with Staphylococcus aureus V8 proteinase, chymotrypsin, or papain followed by gel electrophoresis were identical to corresponding peptide maps of P-450(14DM). However, P-450SG1 showed no lanosterol 14 alpha-demethylase activity and its mode of interaction with diniconazole [(E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-y1)-1- penten-3- o1], a specific inhibitor of P-450(14DM), was fundamentally different from that of P-450(14DM). The absorption spectrum of ferric P-450SG1 was unusual for a native low-spin cytochrome P-450 and was superimposable on that of 1-methylimidazole complex of P-450(14DM), indicating that P-450SG1 has a histidine 6th ligand trans to the thiolate 5th ligand, while the 6th ligand of other ferric low-spin cytochrome P-450s is a water molecule or a hydroxyl group of an oxyamino acid. It is concluded that P-450SG1 is an altered P-450(14DM). Difference in the primary structure between P-450SG1 and P-450(14DM) may be slight and was not detected by peptide mapping. However, the alteration caused significant change in the substrate site and heme environments of the cytochrome. P-450SG1 is the first example of a cytochrome P-450 having a histidine axial ligand trans to thiolate and of a genetically altered cytochrome P-450 isolated in a homogeneous state.
...
PMID:Isolation and characterization of an altered cytochrome P-450 from a yeast mutant defective in lanosterol 14 alpha-demethylation. 311 90

A growth factor which stimulates DNA synthesis in resting mouse Balb/c 3T3 cells (3T3 cells) has been extracted from human follicular ovaries and partially purified. The dialyzed cytosol stimulated 3H-DNA synthesis in 3T3 cells dose-relatedly. When the extract was subjected to salting-out procedures with ammonium sulfate, there was found a 60% saturation cut containing growth promoting activity. Ion exchange on a cation exchanger of the active 60% cut produced an active fraction in the 1M NaCl elute. Gel filtration of ovarian cytosol yielded an active fraction that eluted between chymotrypsin (25,000 MW) and cytochrome C (12,400 MW). The data presented here indicate the presence of an endogenous growth factor in human ovary. The factor appears to be a basic protein, heat-labile and soluble in 40% or less ammonium sulfate, with a molecular weight of between 12,400-25,000. With respect to the biochemical characteristics, this growth factor is quite similar to the porcine ovarian growth factor previously reported.
...
PMID:[An endogenous growth factor extracted from the human ovary]. 372 50


1 2 3 4 Next >>

---