Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amino acid sequence of the mature protein of Euglena gracilis cytochrome c1 was determined by sequencing of its cDNA. A cDNA expression library was constructed from Euglena poly(A)+ RNA in phage lambda gt11 and screened with an antiserum raised against cytochrome c1 polypeptide isolated from purified E. gracilis complex III. An isolated cDNA clone consisted of 872 base pairs and encoded the mature protein with 243 amino acids. The deduced amino acid sequence contained the unusual heme binding sequence-Phe-Ala-Pro-Cys-His- (Mukai, K. et al. (1989) Eur. J. Biochem. 178, 649-656) instead of the typical sequence,-Cys-X-Y-Cys-His-, commonly found in C-type cytochromes. Comparison of the sequence with those of several other cytochromes c1 revealed that Euglena cytochrome c1 conserved the residues probably ligating heme-iron, those supposed to interact with cytochrome c and regions anchoring the mitochondrial inner membrane.
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PMID:Molecular cloning and nucleotide sequence of a cDNA encoding Euglena gracilis cytochrome c1. 255 10

The protein molecule epidermal growth factor (EGF) exerts powerful effects on mouse physical development, since repeated subcutaneous administrations of murine EGF (3.5 mg/kg, from postnatal day 2 to postnatal day 10) cause precocious eyelid opening (as early as day 8 instead of day 13 in control littermates receiving 3.5 mg/kg cytochrome c) and precocious eruption of the lower incisors (day 6 instead of day 8). By contrast, the same EGF treatment retards both the rate of body growth and the full appearance of several neurobehavioral signs of maturation, such as righting and grasping responses. Neonatal mice receiving 5 mg/kg murine nerve growth factor (NGF) under the same treatment schedule, although showing a significant retardation in body weight gain, exhibited only limited changes in neurobehavioral maturation. Specifically, the appearance of slow and swift righting, response to strong tactile stimulation, hindlimb and forelimb grasping, pole grasping, and vertical screen and screen climbing were significantly retarded by EGF and slightly advanced by NGF (the only significant NGF effect was an acceleration of swift righting maturation). Polypeptide growth factors seem to play an important role in physical and neurobehavioral development of altricial rodents, orchestrating the relative maturation of different tissutal targets on different developmental stages.
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PMID:Epidermal growth factor has both growth-promoting and growth-inhibiting effects on physical and neurobehavioral development of neonatal mice. 278 6

1. Several bird and fish heart mitochondrial cytochrome c oxidases have been isolated with a rapid and simple method involving hydrophobic and affinity chromatography. 2. Their spectrophotometric and kinetic properties are very similar to those of the mammalian enzymes. 3. These oxidases show a polypeptide composition simpler than the mammalian enzymes being composed of 9-10, instead of 13, different polypeptides. 4. These data suggest that the complexity of the mitochondrial heart oxidase increases with the stage of evolution.
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PMID:Isolation and characterization of cytochrome c oxidase from bird and fish heart mitochondria. 282 48

Ferredoxin has been effectively cross-linked to photosystem I complex by treatment of purified particles or thylakoids with N-ethyl-3-(3-dimethylaminopropyl)carbodiimide, a zero-length cross-linker which stabilizes protein-protein electrostatic interactions. Analysis of photosystem I polypeptide composition after such a treatment showed a specific decrease of the 20-kDa subunit and the appearance of a new component of about 42 kDa which was recognized by the anti-ferredoxin antibody. Cross-linking of ferredoxin to thylakoids allowed the membrane preparation to photoreduce cytochrome c without requiring exogenous ferredoxin, whereas photosystem I particles purified from treated thylakoids were inactivated in the NADP+ photoreduction activity. From these results, it can be inferred that the polypeptide of 20 kDa is the photosystem I subunit which interacts with ferredoxin during the photosynthetic electron transport.
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PMID:Interaction between photosystem I and ferredoxin. Identification by chemical cross-linking of the polypeptide which binds ferredoxin. 282 98

The amino acid sequences of the cytochromes c-554(548) and c' from the moderately halophilic bacterium Paracoccus sp., I.A.M. 203 (= A.T.C.C. 12084, N.C.I.B. 8669) have been determined. Cytochrome c-554(548) consists of a single polypeptide chain of 83 residues, and dimerizes strongly. The most similar protein of known sequence is the N-terminal half of the dihaem cytochrome c4, and other related proteins include the cytochrome c-554(547) of Thiobacillus neapolitanus and the cytochrome c-553 of Desulfovibrio vulgaris. Cytochrome c', which has a single polypeptide chain of 132 residues, is similar in sequence to cytochromes c' from phototrophic and denitrifying bacteria, but only shows about 36% sequence identity to the most similar protein of known sequence. Both of the Paracoccus proteins have a considerable excess of acidic amino acid side chains over basic ones, and a higher proportion of their basic amino acids is arginine than is usual in cytochromes c. Both these characteristics seem to be adaptations to increase the stability of the proteins in an environment of high ionic strength. Detailed evidence for the amino acid sequences of the proteins has been deposited as Supplementary Publication 50140 (24 pp.) at the British Library (Lending Division), Boston Spa, Yorkshire LS23 7BQ, U.K. from which copies are available on prepayment.
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PMID:Amino acid sequences of cytochrome c-554(548) and cytochrome c' from a halophilic denitrifying bacterium of the genus Paracoccus. 282 28

A method is described for the preparation of polypeptides activated uniquely at the C-terminus. The polypeptide is incubated in a concentrated solution of an amino acid active ester, the latter having its amino group free but adequately protected by protonation. The amino acid ester is coupled via its amino group to the C-terminus of the polypeptide by enzymic catalysis (reverse proteolysis). The resulting polypeptide C-terminal active ester is then isolated and coupled to a suitable amino component (generally a polypeptide) in a subsequent chemical coupling. The method appears to be generally applicable; fragments of horse heart cytochrome c, and porcine insulin, are used as examples. Two new analogues of cytochrome c have been prepared by using this method, with yields of up to 60% in the final coupling. Scope and limitations of the method are discussed.
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PMID:Enzyme-assisted semisynthesis of polypeptide active esters and their use. 282 52

A molecular replacement approach, augmented with the results of predictive modeling procedures, solvent accessibility studies, packing analyses and translational coefficient searches, has been used to elucidate the 2.8 A (1 A = 0.1 nm) resolution structure of yeast iso-1-cytochrome c. An examination of the polypeptide chain folding of this protein shows it to have unique conformations in three regions, upon comparison with the structures of other eukaryotic cytochromes c. These include: residues -5 to +1 at the N-terminal end of the polypeptide chain, which are in an extended conformation and project in large part off the surface of the protein; residues 19 to 26, which form a surface beta-loop on the His18 ligand side of the central heme group; and, the C-terminal end of the helical segment composed of residues 49 to 56, which serves to form a part of the heme pocket. Structural studies also show that the highly reactive sulfhydryl group of Cys102 is buried within a hydrophobic region in the monomer form of yeast iso-1-cytochrome c. Dimerization of yeast iso-1-cytochrome c through disulfide bond formation between two such residues would require a substantial conformational change in the C-terminal helix of this protein. Another unique structural feature, the trimethylated side-chain of Lys72, is located on the surface of yeast iso-1-cytochrome c near the solvent-exposed edge of the bound heme prosthetic group. On the basis of the results of these and other structural studies, an analysis of the spatial conservation of structural features in the heme pocket of eukaryotic cytochromes c has been conducted. It was found that the residues involved could be divided into three general classes. The current structural analyses and additional modeling studies have also been used to explain the altered functional properties observed for mutant yeast iso-1-cytochrome c proteins.
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PMID:Yeast iso-1-cytochrome c. A 2.8 A resolution three-dimensional structure determination. 283 11

A quinol-cytochrome c oxidoreductase (cytochrome bc1 complex) has been purified from plasma membranes of a thermophilic Bacillus, PS3, by ion-exchange chromatography in the presence of Triton X-100. The purified enzyme shows absorption bands at 561-562 nm and 553 nm at room temperature, and 560, 551, and 547 nm at 80 K upon reduction, and gives an ESR signal similar to that of a Rieske-type iron sulfur center. Its contents of protohemes, heme c, and non-heme iron are about 23, 10, and 21 nmol/mg of protein, respectively. The enzyme consists of four polypeptides with molecular masses of 29, 23, 21, and 14 kDa judging from their electrophoretic mobilities in the presence of sodium lauryl sulfate. Since the staining intensities of the respective bands are almost proportional to their molecular masses, the monomer complex (87 kDa) of the subunits probably consists of a cytochrome b having two protohemes, a cytochrome c1 and an Fe2-S2-type iron sulfur center. The 29 and 21 kDa subunits were identified as cytochromes c1 and b, respectively, and the 23-kDa subunit is probably an iron-sulfur protein, since the 14-kDa polypeptide can be removed with 3 M urea without reducing the content of non-heme iron. Several characteristics of the subunits and chromophores indicate that the PS3 enzyme is rather similar to cytochrome b6f (a bc1 complex equivalent) of chloroplasts and Cyanobacteria. The PS3 complex catalyzes reduction of cytochrome c with various quinol compounds in the presence of P-lipids and menaquinone. The turnover number at pH 6.8 was about 5 s-1 at 40 degrees C and 50 s-1 at 60 degrees C. The enzyme is heat-stable up to 65 degrees C.
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PMID:Quinol-cytochrome c oxidoreductase from the thermophilic bacterium PS3. Purification and properties of a cytochrome bc1(b6f) complex. 283 71

Ubiquinol-cytochrome c oxidoreductase (cytochrome bc1) complex from Paracoccus denitrificans consists of only three polypeptide subunits (Yang, X., and Trumpower, B. L. (1986) J. Biol. Chem. 261, 12282-12289), whereas the analogous complexes of eukaryotic mitochondria consist of nine or more polypeptides (Schagger, H., Link, T. A., Engel, W. D., and von Jagow, G. (1986) Methods Enzymol. 126, 224-237). Using the purified three-subunit Paracoccus complex we have tested whether this simple cytochrome bc1 complex has the same electron transfer pathway and proton translocation activity as the bc1 complexes of mitochondria. Under presteady state conditions, the effects of inhibitors on reduction of cytochromes b and c1 by quinol and oxidant-induced reduction of cytochrome b indicate a cyclic electron transfer pathway and two routes of cytochrome b reduction in the three-subunit Paracoccus cytochrome bc1 complex. A novel method was developed to incorporate the cytochrome bc1 complex into liposomes with the detergent dodecyl maltoside. The enzyme reconstituted into liposomes translocated protons with an H+/2e value of 3.9. Carbonyl cyanide m-chlorophenylhydrazone eliminated proton translocation, while permitting the scalar release of protons from quinol, and thus reduced the H+/2e ratio to 2. These values agree with the predicted stoichiometries for proton translocation by a protonmotive Q cycle pathway. No inhibition of proton translocation by N',N'-dicyclohexylcarbodiimide was detected when the Paracoccus cytochrome bc1 complex was incubated with N',N'-dicyclohexylcarbodiimide before or after reconstitution into liposomes. Electron transfer in the three-subunit complex thus appears to occur by a protonmotive Q cycle pathway identical to that in mitochondrial cytochrome bc1 complexes. Only three polypeptides, cytochromes b, c1, and the Rieske iron-sulfur protein, are required for respiration and energy transduction in the cytochrome bc1 complex. The function of the supernumerary polypeptides in mitochondrial bc1 complexes is thus unclear.
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PMID:Protonmotive Q cycle pathway of electron transfer and energy transduction in the three-subunit ubiquinol-cytochrome c oxidoreductase complex of Paracoccus denitrificans. 284 40

To understand the process of protein folding, it will be necessary to obtain detailed structural information on folding intermediates. This difficult problem is being studied by using hydrogen exchange and rapid mixing to label transient structural intermediates, with subsequent analysis of the proton-labelling pattern by two-dimensional nuclear magnetic resonance spectroscopy. Results for cytochrome c show that the method provides the spatial and temporal resolution necessary to monitor structure formation at many defined sites along the polypeptide chain on a timescale ranging from milliseconds to minutes.
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PMID:Structural characterization of folding intermediates in cytochrome c by H-exchange labelling and proton NMR. 284 79


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