Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thermal transitions of native lysozyme and a well-characterized cross-linked derivative of lysozyme [Imoto, T., and Rupley, J. A. (1973), J. Mol. Biol. 80, 657] have been studied in 1.94 M guanidine hydrochloride at pH 2. The observed increase in the melting temperature from 32.4 degrees C for native lysozyme to 61.8 degrees C for the cross-linked derivative corresponds to a calculated 5.2 kcal/mol increase in the free energy of denaturation. This free-energy change is attributed to the decreased entropy of the unfolded polypeptide chain following introduction of a cross-link and is shown to compare well with theoretical predictions. The possibility that an introduction of a cross-link could also affect the enthalpy of an unfolded protein was investigated. The heats of reduction of bovine serum albumin and lysozyme by dithioerythritol in 6 M guanidine hydrochloride were determined and compared to that for the model peptide, oxidized glutathione. The near identity of the observed heats was taken as evidence that the introduction of cross-links into a random-coil protein does not, in general, introduce strain.
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PMID:Thermodynamics of protein cross-links. 64 96

The conformation of some regular polypeptides: (Lys-Ala)50, (Lys-Ala2)37, (Lys-Ala2)26, (Lys-Ala3)18, (Lys3-Pro)29, (Orn3-Gly)28 was studied by means of CD. The complexes of these polypeptides with DNA were obtained by the methods of jump-dilution of a two-components mixture from 2 M NaCl to 0.05 M NaCl. The extent of DNA covering by the polypeptides was compared using binding isoterms of ethidium on DNA and DNA-polypeptide complex. The length, L, which polypeptides cover on DNA was estimated by means of energy transfer between the dyes absorbed on the complexes. The CD spectra of the complexes revealed a high sensitivity to changes of the environmental conditions. Small variations in the temperature and ionic strength produces marked changes in the CD spectra of the complexes. It was suggested that observed CD changes are due to both the structural relaxation of the complexes and the existence of liquid-crystal domains in solution.
Mol Biol (Mosk)
PMID:[Structure of DNA complexes with regular polypeptides]. 65 74

A challenging theme in bioorganic chemistry is the unification of established theories of biochemistry and organic chemistry to provide new patterns for interpretation and experimentation. Especially relevant examples of such interactions can be drawn from the field of enzyme catalysis and, in particular, the role of cofactors therein. Knowledge of the chemical mechanisms by which some of the cofactors function has progressed rapidly with the aid of studies of the cofactors themselves (or compounds of related structure, "models") stripped of the accompanying apoenzyme. The striking successes in this field likely arise from a fundamental resemblance between bioorganic chemistry (especially coenzyme models) and chemical evolution before the appearance of coded polypeptide enzymes.
J Mol Evol 1978 Jun 20
PMID:Bioorganic chemistry and the origin of life. 67 63

A protein which binds the insect juvenile hormone has been isolated from the hemolymph of the fourth instar tobacco hornworm, Manduca sexta (Lepidoptera). Bioassay and chemical characterization of the bound ligand from the purified binding protein indicates that this molecule is the primary macromolecule responsible for juvenile hormone transport in the hemolymph of this insect. The juvenile hormone binding protein has been purified using gel filtration, ion exchange chromatography and preparative polyacrylamide gel electrophoresis. The protein is a single polypeptide chain of about 28,000 daltons with a sedimentation coefficient of 2.2S and an isoelectric point of 5.0. Binding analysis using a hydroxyapatite batch assay indicates that the juvenile hormone binding protein has one binding site with a Ka of 1.2 times 10(7) M-1 at 4 degrees C.
Mol Cell Endocrinol
PMID:Purification and characterization of a juvenile hormone binding protein from the hemolymph of the fourth instar tobacco hornworm, Manduca sexta. 68 Mar 42

Rough endoplasmic reticulum membranes were dissolved in 1% deoxycholate and the deoxycholate was then dialysed out for five days. Well-defined bilayer vesicles were formed only if the dialysis was performed at room temperature for the first six hours. The vesicles were separated into a pelleted fraction (Fraction 1) and a fluffy layer (Fraction II) by centrifugation. As measured by amino acid incorporation ability, Fraction II bound polysomes, while Fraction I did not. When smooth endoplasmic reticulum was assembled, it was found that Fraction II so derived had a polysome binding capacity which was more sensitive to increased KCl concentrations (25 mM - 100 mM KCl) and that it bound significantly more monosomes than the corresponding fraction derived from rough membranes. The SDS-polyacrylamide polypeptide patterns of the various fractions were compared.
Mol Biol Rep 1978 Jun 16
PMID:The in vitro reassembly of rough endoplasmic reticulum: ribosome binding capacity. 68 83

The amino acid sequences of the tryptic peptides of the thiol proteinase actinidin from Actinidia chinensis were determined by the manual dansyl--Edman procedure. There are 12 tryptic peptides, which give a polypeptide chain of 220 residues with a mol.wt. of 23500. An alignment of the tryptic peptides was made by using the X-ray-crystallographic data of Baker [(1977) J. Mol. Biol. 115, 263--277] determined at 0.28 nm resolution on crystalline actinidin. Detailed evidence for the amino acid sequences of the tryptic peptides has been deposited as Supplementary Publication SUP 50083 (14 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.
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PMID:The amino acid sequence of the tryptic peptides from actinidin, a proteolytic enzyme from the fruit of Actinidia chinensis. 68 80

Ca2+-entry into intact red cells containing [32P]-ATP increases the phosphorylation of the 150 000 dalton polypeptide of the membrane. This phosphorylation occurs even in Mg2+-depleted red cells. Extracellular lanthanum applied during ATP-depletion further increases the Ca2+-induced phosphorylation. In fragmented membranes or resealed insideout vesicles (IOVs) membrane bound Mg2+ is sufficient to catalyze the phosphorylation of spectrin 2 and Band 3 polypeptides with low concentrations (less than micron of [32P]-ATP. In Ca-EDTA buffers one single polypeptide is phosphorylated which is located in the 150 000 molecular weight region. KmCa for phosphorylation is much lower (0.2 micron) than for active Ca2+ transport (40 micron) in IOVs. Lanthanum induced phosphorylation (up to 250 micron Lafree) is significantly greater than Ca2+-induced phosphorylation. Hg2+ inhibits both Ca2+ and La3+ induced phosphorylation. Ca2+-induced labelling can be rapidly "chased" by unlabelled ATP+Mg2+, but not with EGTA+Mg2+. Dephosphorylation in Ca2+ phosphorylated membranes and IOVs is significantly inhibited by La3+. It can be concluded that the mechanism of La3+ and Hg2+ inhibition of the Ca2+ pump is different in intact cells and isolated membranes or Iovs.
Mol Cell Biochem 1978 Dec 22
PMID:Phosphorylation of the Ca2+ pump intermediate in intact red cells, isolated membranes and inside-out vesicles. 74 97

The mode and site of action of inhibitors of translation (initiation, elongation and termination of protein synthesis) in eukaryotic systems is reviewed. The isolation and characterization of a factor is described that binds Ac-Phe-tRNA to form a complex made up of binding factors, Ac-Phe-tRNA, and ribosome. The binding of Ac-Phe-tRNA probably occurs at the ribosomal site involved in the binding of the initiator substrate Met-tRNAF. The effect of inhibitors of the intitiation phase of protein synthesis on the nonenzymic Ac-Phe-tRNA binding to ribosomes is investigated. The two sites translocation model for translation in eukaryotic cells is presented and the effects of inhibitors on the various steps of protein synthesis are determined empirically. The site of action of inhibitors of peptide bond formation at the ribosomal peptidyl transferase center is elucidated. The action of inhibitors of translocation is sutdied in model cell-free systems from human cells. In addition, a number of methylxanthines are shown to enhance the elongation phase in polypeptide synthesis by stimulating the enzymic binding of aminoacyl-tRNA. The effect of caffeine, theophylline and its derivatives are shown to be fairly specific and dependent on the ribosome concentration. Aminophylline is shown to have a similar effect but also enhances aminoacyl-tRNA synthetase activity at low Mg++ concentrations, probably displacing the optimal concentration of Mg++ in the reaction. This second effect of aminophylline appears to be due to the ethylenediamine moiety of aminophylline since it is also observed in the presence of different polyamines but not in the presence of caffeine or theophylline.
Mol Cell Biochem 1976 Feb 16
PMID:Antibiotics and compounds affecting tanslation by eukaryotic ribosomes. Specific enhancement of aminoacyl-tRNA binding by methylaxnthines. 76 41

Treatment of elongation factor G (EF-G) with the thiol reagent N-ethylmaleimide only partially inhibits (10 to 70%) the activity of the factor in (a) guanosine nucleotide-EF-G-ribosome complex formation, (b) uncoupled ribosome-dependent GTP hydrolysis, and (c) polypeptide synthesis. Moreover, a similar treatment of the factor with N-[3H]ethylmaleimide does not lead to 3H-label being associated with a GDP-EF-G-ribosome-fusidic acid complex. Thus, the results indicate the presence in EF-G preparations of a form of the factor that does not react with N-ethylmaleimide.
Mol Biol Rep 1976 Apr
PMID:A form of elongation factor G insensitive to N-ethyl-maleimide. 77 17

By modifying four tyrosine residues in pepsin a derivative (aminopepsin) is obtained which is capable to conjugate with a fluorescent label DNS-Cl without loss of the catalytic activity. Rotational relaxation times of native pepsin and dansylated aminopepsin (DAP) are measured by a fluoresence polarization method. The values obtained are shown to be lower than those calculated for arigid pepsin globule. Possible sources of the obtained difference are discussed. A reversible or covalent blocking of pepsin or DAP active centres by specific inhibitors leads to an increase in rotational relaxation time values for these proteins reaching the magnitude which is very close to that calculated for a model of rigid pepsin. Brownian relaxation of pepsin and DAP reduced by beta-mercaptoethanol and of pepsinogen and some fragments of pepsine macromolecule in aqueous solutions is invigated as well. The results are intepreted as representing an intramolecular mobility or segmental flexibility of pepsin and DAP. With the use of the obtained and X-ray data a segmental model of dynamic pepsin structure is suggested. On the basis of this model some conclusions are drawn concerning a localization of a polypeptide which is split off from the N-terminus of pepsinogen during its activation. A possible role of segmental flexibility in the catalytic action of pepsin is considered.
Mol Biol (Mosk)
PMID:[Intramolecular mobility of pepsin]. 78 36


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