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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The incorporation of [3H]-glucosamine into polypeptides of three fractions of polysomes in MPC-11 cells was studied. After short term incubation greatest incorporation was observed in a fraction of membrane-bound polysomes, which after nitrogen cavitation of cells, remained bound to the endoplasmic reticulum (ER) associated with the nucleus (fraction 2). Polypeptide chains on membrane-bound polysomes in the microsomal fraction (fraction 1) and free polysomes contained much less radioactivity. Since nascent polypeptide chains contained within membrane-bound polysomes of fraction 2 are glycosylated at an earlier stage than those in fraction 1 it is likely that this represents a difference in type of proteins synthesized in the respective fractions of ER.
Mol Biol Rep 1979 Feb 15
PMID:Differences in the incorporation of [3H]-glucosamine into nascent polypeptide chains on free polysomes and two fractions of membrane-bound polysomes in mouse myeloma cells. 44 Mar 1

The dependence of the nitrogen reduction rate on N2-concentration under high nitrogen pressures was measured. The reason for the sharp break of the Arrenius curves in nitrogenase reactions at 20 degrees C was examined. The influence of nitrogen on isotope effect catalyzed by nitrogenase was studied. The kinetic schemes that explain the peculiarities of the nitrogenase reactions were analyzed by the graph's theory. On the base of new conception of inhibitor-"interceptor" of electrons the literature data were discussed.
Mol Biol (Mosk)
PMID:[Several kinetic features of nitrogenase reactions]. 44 Mar 7

The intermolecular interaction of bacteriochlorophyll c and its pheophytin was studied in nonpolar solvents and solid films with the aid of absorption and infra-red (in the region of 1800--1600 and 3800--3000 cm-1) spectra. The influence of water removing and its addition on these spectra has been investigated. Besides the effect of pyridine treatment and pigment concentration were examined. The self-assemblage of all types of bacteriochlorophyll c aggregated forms absorbing in the range 680--745 nm is due to the formation of intermolecular bonds in which keto groups of cyclopentanone rings take part. Keto groups form coordinate bonds with the central magnesium atom (keto-C = O...Mg). Hydroxyl groups interact coordinately with magnesium and simultaneously form hydrogen bonds with pyrrol nitrogen. In contrast to chlorophyll a and bacteriochlorophyll a, water molecules in the case of bacteriochlorophyll c do not participate in the intermolecular bond formation in the course of long-wave aggregated forms production. The thermostability of bacteriochlorophyll c aggregates and their rather high stability to desaggregating agents is related to the mentioned peculiarities of their structure. Bacteriopheophytin c in any state (solution or solid film) is not capable to form intermolecular bonds by its carbonyl groups and long-wave aggregates. The specific features of the assemblage of bacteriochlorophyll c aggregates modelling antenna of the green photosynthetic bacteria are discussed.
Mol Biol (Mosk)
PMID:[Molecular mechanism of self-assembly of aggregated bacteriochlorophyll c]. 46 Feb 4

The DNA helix-coil transition in the presence of ligands interacting selectively with a certain type or types of base pairs has been considered. A calculation method for estimation the influence of lignads on the melting process for which the knowledge of DNA primary structure is not required was proposed. It has been shown that the reverse temperature shift caused by ligands bound to a given type of base pairs at given kind of regions (helix or coli) is in direct proportion to the fist derivative with respect to the degree of helicity from ratio beta ji/n, where beta ji--number of nitrogen bases of i-type at the regions of j-kind; N--total number of DNA base pairs. It was assumed earlier that this shift was in direct proportion to beta ji/Nj, where Nj--number of base pairs in DNA regions of j-kind. The specificity of lignads interaction with given kinds of bases alters the manner of the melting process of the heteropolynucleotide in comparison with homopolynucleotide only in the case when the DNA primary structure has a strong influence on the position of helix and coli regions along the DNA chain. Only when this conditions is fulfilled the inversion of thermostability of AT- and GC-pairs may affect the shape of the melting curve.
Mol Biol (Mosk)
PMID:[Influence of ligands characteristic of selective binding to a certain type of base pairs on DNA helix-coil transition I. Model. Theory]. 50 59

Nonbonded interaction energy calculations were performed for complementary deoxydinucleoside phosphate complexes dApdA with dUpdU and dUpdA with dUpdA. All dihedral and bond angles but nitrogen base angles were the variables in minimization of energy. Complex conformations resembling A- and B-family double-helical conformations were recieved as a result of calculations when intramolecular interaction energy approach minima. Dihedral angles of one molecule of the complex may differ from corresponding angles of another by several degrees. Energy optimal complex conformations in other space regions of conformation parameters were found. Biological consequences of possible dihedral and bond angle changes of double stranded nucleic acids at interactions with other molecules are discussed.
Mol Biol (Mosk)
PMID:[Simulation of DNA conformation possibilities by means of nonbonded interaction energy calculations of complementary dinucleoside phosphate complexes]. 74 5

When in the primeval atmosphere ammonia approached exhaustion, bacteria resembling clostridia developed mechanisms for nitrogen fixation. The fixation was continued by the photosynthetic bacteria. In the later, oxidizing, atmosphere the combined activities of the nitrificants and the denitrificants could lead to a large-scale cyclic regeneration of free nitrogen. The possibility of a descent of the nitrificants from hypothetical photosynthetic bacteria, which used ammonia as electron donor, is discussed. The anoxygenic atmosphere contained no nitrate, and therefore neither nitrate fermentation nor nitrate respiration were precursors of aerobic respiration. This evolved from photosynthesis. In nitrate fermentation, nitrate serves only as an incidental electron acceptor; this process is merely an evolutionary sideline. Nitrate respiration evolved from aerobic respiration. While in present conditions the reaction of nitrogen with oxygen and water to give nitrate is exergonic and possibly occurs at a low rate, the antagonistic action of the denitrificants maintains the stationary concentrations of nitrogen and oxygen in the air.
J Mol Evol 1975 Dec 31
PMID:The history of inorganic nitrogen in the biosphere. 76 87

1. Venous blood concentrations of the branched-chain amino acids, valine, leucine and isoleucine, and urinary nitrogen excretion have been measured in sixteen adult males, from 2 h to 7 days after injury, and in four adults after elective skin grafts. 2. In the injured group the concentrations of these amino acids rose significantly 24 h after injury and had doubled at 4 days and remained high; in contrast the skin-graft patients showed no significant change. 3. In those injured patients with initial hyperketonaemia, defined as more than 0-2 mmo1/1, the increase in concentrations of branched-chain amino acids at the fourth and seventh days after injury was significantly less than in those with normoketonaemia, and was accompanied by lower urinary nitrogen excretion throughout the whole period. 4. It is suggested that the changes in the concentration of branched-chain amino acids after injury indicate decreased uptake by muscle or excessive release due to an imbalance between protein synthesis and protein catabolism in this tissue.
Clin Sci Mol Med 1976 May
PMID:Branched-chain amino acids, nitrogen excretion and injury in man. 77 95

Sakakibara and Tomizawa (1974a) have described a soluble in vitro system that can carry the semi-conservative replication of the Co1 E1 plasmid. However, the usefulness of this system is restricted by its rapid inactivation during storage. This paper describes a stable soluble system prepared by freeze-thaw lysis of chloramphenicol-treated E. coli cells which replicates added Co1 E1 and C1o DF13 DNA. It differs from the system employed by Sakakibara and Tomizawa in two important points: (1) Its replicative capacity for Co1 E1 DNA is by an order of magnitude higher and (2) it can be stored in liquid nitrogen for several months without loss of activity Plasmid replication in vitro is dependent of DNA polymerase I and requires de novo RNA synthesis. It is completely inhibited by rifampicin, oxolinic acid, and novobiocin. The DNA synthesized during a 60 min incubation at 30 degrees C consists mostly of monomeric supercoils. If Co1 E1 DNA is used as template, a minor portion of the label is also found in closed dimeric catenanes. Density labelling experiments indicate that plasmid DNA synthesis occurs by a semi-conservative replication process.
Mol Gen Genet 1976 Jun 15
PMID:Replication of small plasmids in extracts of Escherichia coli. 78 16

The transcriptional and translational events occurring during the induction of the lac operon, were separated by blocking the translational step, either by aminoacid starvation or by addition of chloramphenicol. It was found that the carbon source used during the subsequent translation, affected the rate of beta-galactosidase synthesis. A decoordination effect on the production of enzymes of the lac system was also observed in high catabolite repression media, as well as in nitrogen limiting conditions. These findings suggested a similarity with the polarity phenomenon. In order to test this similarity, polarity suppressors of a Z- polar mutant were isolated. In one of these mutants, probably suA like, no carbon source effect was observed during the translational step. The induction kinetics in different media, after distinct pregrowth conditions, supported the idea that this mutant could be considered catabolite repression resistant only in certain restrictive conditions.
Mol Gen Genet 1976 Oct 18
PMID:Catabolite translational effects on the lac messenger RNA of Escherichia coli K12. 79 85

Mutants of A. nidulans at several loci lack detectable NADPH-nitrate reductase activity. These loci include niaD, the structural gene for the nitrate reductase polypeptide, and five other loci termed cnxABC, E, F, G and H which are presumed to be involved in the formation of a molybdenum-containing component (MCC) necessary for nitrate reductase activity. When forzen mycelia from A. nidulans deletion mutant niaD26 were homogenized in a Ten Broeck homogenizer together with frozen mycelia from either cnxA6, cnxE29, cnsF12, cnxG4 or cnxH3 strains grown on urea + nitrate as the nitrogen source, nitrate reductase activity was detectable in the extract. Similar results were obtained by co-homogenizind niaD mycelia with Neurospora crassa nit-1 mycelia induced on nitrate. Thus, all A. nidulans cnx mutants are similar to the N. crassa nit-1 strain in their capacity to yield NADPH-nitrate reductase in the presence of the presumed MCC. As judged by the amounts of nitrate reductase formed, niaD26 mycelia grown on urea +/- nitrate contained much more available MCC than ammonium-grown mycelia. No NADPH-nitrate reductase activity was found in extracts prepared by co-homogenizing mycelia from all five A. nidulans cnx strains. Wild-type A. nidulans NADPH-nitrate reductase acid dissociated by adjustment to pH 2.0-2.5 AND RE-ADJUSTED TO PH 7 could itself re-assemble to form active nitrate reductase and thus was not a useful source of MCC for these experiments. These results are consistent with the conclusion that the active nitrate reductase complex is composed of polypeptide components which are the niaD gene product, plus the MCC which is formed through the combined action of the cnx gene products. Further, the production of MCC may be regulated in response to the nitrogen nutrition available to the organism.
Mol Gen Genet 1976 Dec 08
PMID:Formation of NADPH-nitrate reductase activity in vitro from Aspergillus nidulans niaD and cnx mutants. 79 78


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