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

The splanchnic-hepatic metabolism of glucose, lactate, pyruvate, alanine, glycerol, non-esterified fatty acids (NEFA), ketone bodies and oxygen were investigated in five normal men and six juvenile diabetic subjects at rest and during exercise after an overnight fast. A linear relationship was found between load (arterial concentration multiplied by hepatic blood flow) and splanchnic-hepatic uptake of lactate, pyruvate, glycerol and NEFA. The uptake of alanine was highly sensitive to load, but was also regulated by the concentration of hepatic venous glucagon. The uptake of pyruvate was high in exercising diabetic subjects, who had a high lactate/pyruvate concentration ratio in hepatic venous blood. The rate of uptake of the total measured gluconeogenic precursors was significantly higher in the diabetic group at a given load. The rate of ketogenesis was linearly related to the NEFA load in both groups; however, the rate of ketogenesis was twofold at a given load in the diabetic group. The highest rates of ketogenesis were found coincident with the highest concentrations of glucagon in hepatic venous blood. The observed antiketogenic effect of exercise was due to a decreased load of NEFA, mainly caused by a decrease in the hepatic blood flow.
Clin Sci Mol Med 1977 Nov
PMID:Regulation of gluconeogenesis and ketogenesis during rest and exercise in diabetic subjects and normal men. 20 21

The action of micrococcal nuclease, DNase I and DNase II on mouse TLT hepatoma chromatin revealing the periodicity of its structure as visualized by denaturing and non-denaturing gel electrophoresis, was consistent with the action of these enzymes on other chromatins. Micrococcal nuclease showed a complex subnucleosome fragment pattern based on multiples of 10 base pairs with a prominant couplet at 140/160 base pairs and the absence of the 80 base pair fragment. This couplet of the core and minimal nucleosome fragments was conspicuously present in the mononucleosomes found in the 11S fractions of a glycerol gradient centrifugation. DNase I and II produced a fairly even distribution of a 10 base pair increasing series of fragments to about 180 base pairs, a pattern also repeated in the DNA of nucleosome glycerol-gradient fractions. In limited digestions by these nucleases multinucleosomic DNA fragments are pronounced. These fragment lengths are multiples of an estimated average repeat length of nucleosome DNA of 180 base pairs. The action of the endogenous Mg/Ca-stimulated endonuclease produced only limited cuts in the hepatoma chromatin resulting primarily in multi-nucleosomic DNA fragment lengths and only upon lengthy digestion limited subnucleosomic, 10-base-pair multiple fragments are produced. The putative euchromatin-enriched fractions (50-75S) of the glycerol gradient centrifugation of autodigested chromatin, similarly, contained primarily the multinucleosomic DNA fragment lengths. These results are consistent with our previous electron microscopic demonstration that autodigested chromatin as well as the putative euchromatin-enriched fractions were composed of multi-nucleosomic chromatin segments containing a full complement of histones.
Mol Cell Biochem 1978 Apr 11
PMID:Periodicity and fragment size of DNA from mouse TLT hepatoma chromatin and chromatin fractions using endogenous and exogenous nucleases. 20 20

Lactate dehydrogenase and glycerol 3-phosphate dehydrogenase are metabolically coupled by the anaerobic dismutation of glyceraldehyde 3-phosphate and by the NAD redox state. This causes the concentrations of lactate and glycerol 3-phosphate to accumulate proportionally during anaerobic muscle contraction; these concentrations are high relative to those in aerobic tissues such as liver. We show that the isoenzymes of lactate dehydrogenase and glycerol 3-phosphate dehydrogenase from chicken breast muscle have Km values for lactate and glycerol 3-phosphate, respectively, that are 10-fold higher than the Km values measured for the lactate dehydrogenase and glycerol 3-phosphate dehydrogenase isoenzymes from chicken liver. The association of proportionally higher Km values with the potential for proportionally higher accumulation of substrates suggests that the isoenzymes of lactate dehydrogenase and glycerol 3-phosphate dehydrogenase from chicken muscle have evolved in parallel as a coupled metabolic unit distinct from the coupled isoenzymes in liver. The parallelism observed for the reduced substrates extends to the oxidized substrates, and to the coenzymes, NAD+ and NADH.
J Mol Evol 1978 May 12
PMID:Parallel evolution of pairs of dehydrogenase isoenzymes. 20 78

Rates of synthesis of cyclic 3',5'-adenosine monophosphate (cAMP) were measured in cultures of Escherichia coli aerating without a carbon source. This technique provides a representative measure of adenylate cyclase activity in the absence of inhibition caused by transport of the carbon source. Adenylate cyclase activity was found to vary more than 20-fold depending on the carbon source that had been available during growth. Synthesis of cAMP in cells aerating in the absence of the carbon source was highest when cells had been grown with glucose or fructose which inhibit adenylate cyclase activity severely. Synthesis of cAMP was much lower when cells had been grown with glycerol or succinate which cause only minimal inhibition of the activity. The variation in cAMP synthesis due to different carbon sources requires a functional cAMP receptor protein (CRP). Crp- mutants synthesize cAMP at comparable rates regardless of the carbon source that afforded growth. A novel mutant of E. coli having a CRP no longer dependent on cAMP has been isolated and characterized. Adenylate cyclase activity in this mutant no longer responds normally to variations in the carbon source.
Mol Gen Genet 1978 Sep 20
PMID:The cyclic 3',5'-adenosine monophosphate receptor protein and regulation of cyclic 3',5'-adenosine monophosphate synthesis in Escherichia coli. 21 2

The rate of water proton relaxation of the solutions of human serum albumin (HSA) modified by different spin labels has been investigated by spin echo technique. The rate of proton relaxation in the presence of the labeled HSA is higher than that in water solutions of spin labels. The proton relaxation data of the protein solutions can be explained by local properties of the water, bound with the protein (in the regions of spin labels) which seem to resemble those of water-glycerol solutions. The rate of proton relaxation was decreased in the presence of steroids that can be explained by a decrease of the local microviscosity of the water-protein matrix due to interaction of steroids with HSA.
Mol Biol (Mosk)
PMID:[Interaction of steroids with human serum albumin by spin echo technique and paramagnetic sound methods]. 22 29

The binding of ethidium bromide and acriflavin dyes with DNA modified with a spin-labelled analogue of ethylene imine has been studied. These spin-labels were shown to bind covalently to DNA, at the same time the number of the dye molecules bound is decreased without any changes in the binding constant. Analysis of ESR spectra of the samples in the frozen 50% water-glycerol solution at 77 degrees K for spin-labelled DNA has shown that addition of the dyes increases distance between the labels. This fact might be explained by an increase in DNA length upon formation of the complex with dye molecules.
Mol Biol (Mosk)
PMID:[Study of DNA-dye interaction by spin-labels]. 22 30

Three temperature-sensitive mutant strains for RNA polymerase beta or beta' subunits (carrying mutations tsx, A2R7 and R120) were used in order to investigate the dependence of the induced lac expression on stimulation by cyclic AMP after the shift to non-permissive temperature. High temperature lowered the rate of beta-galactosidase synthesis. However, the low rate of synthesis could be strongly increased by cyclic AMP (30, 2.4 and 5.7-fold increases for tsX, A2R7 and R120 mutants, respectively). At the permissive temperature stimulation by cyclic AMP was less than 1.4-fold (minimal medium supplemented with glycerol). The results suggest that the maximal expression of the lac operon is saturated, that is, a hypothetical increase in RNA polymerase or cAMP-CRP concentration in the cell with not enhance the expression. The concept of saturation explains why it was possible to increase the beta-galactosidase synthesis in conditions of limited promoter binding activity of RNA polymerase through increase in concentration of cyclic AMP-CRP complex in the cell (addition of cyclic AMP) to the values higher than that observed on glycerol.
Mol Gen Genet 1979 Jun 20
PMID:Expression of the lac operon in RNA polymerase mutants of Escherichia coli K12. 22 41

Mutants altered in carbon catabolite regulation have been isolated by selecting for mutants of the areA217 strain capable of using acetamide as the sole nitrogen source in the presence of sucrose. In addition to creA mutants described previously be Arst and Cove, strains with mutations in two new genes, creB and cre C, have been found. The creB and creC mutants grow poorly on some sole carbon sources and have low levels of some enzymes of carbon catabolism e.g. beta-galactosidase and D-quinate dehydrogenase. The creB and creC mutants are hypersensitive to fluoroacetate, fluoroacetamide and allyl alcohol in the presence of glucose or sucrose but not glycerol; and the enzymes, acetamidase and alcohol dehydrogenase, are less sensitive to carbon catabolite repression than the wild-type strain. Extracellular protease and alpha-glucosidase enzyme activities are elevated in creB and creC mutants, while L-proline and L-glutamate uptake capacities are lower in both the presence and absence of glucose. Interactions between creA, B and C mutations have been investigated in double mutants, and the dominance properties of creB and creC mutants determined. The results indicate that the creB and creC genes may have a regulatory role in the control of carbon catabolism.
Mol Gen Genet 1977 Jan 18
PMID:Pleiotropic mutants of Aspergillus nidulans altered in carbon metabolism. 32 Apr 55

1. In non-fermentable substrates growth of mutant tsm-8 cells of Saccharomyces cerevisiae is restricted to about one generation after shift from 23 to 35 degrees C. Non-permissive conditions (35 degrees C, glycerol) cause a gradual decrease in respiration to about 20% of the activity at permissive temperature 23 degrees C). 2. Anaerobically grown and glucose-repressed mutant cells exhibit a decreased adaptation rate of mitochondrial functions to aerobic growth and non-fermentative growth, even at 23 degrees C, as revealed by determination of respiratory rates and mitochondrial protein synthesis. 3. At 35 degrees C, rho+ cells of mutant tsm-8 are converted to p- cells within 6-8 generations of growth, in all fermentable substrates tested. Drugs or antibiotics as nalidixic acid, acriflavin, chloramphenicol and erythromycin, bongkrecic acid, antimycin and FCCP, as well as anaerobiosis, have little or no influence on this kinetics. A heat shock does not yield rho- petites to a significant extent. 4. Reversion of tsm-8 cells to wild type function, which occurs spontaneously with a frequency of 10(-8), is found to be due to a mitochondrial mutational event.
Mol Gen Genet 1977 Sep 21
PMID:On the formation of rho- petites in yeast. II. Effects of mutation tsm-8 on mitochondrial functions and rho-factor stability in Saccharomyces cerevisiae. 33 16

S. tyrphimurium strain BY324 is temperature sensitive due to a mutation (rpo C32) in the gene for the RNA polymerase beta' subunit. Transcription of T7 DNA by RNA polymerase purified from this strain is temperature sensitive in vitro. The enzyme is slightly defective in template binding and RNA chain initiation, but the major defect is in RNA chain elongation. The rate of RNA chain elongation is reduced 4-5 fold relative to wild-type. RNA chain termination does not appear to be affected by the beta' mutation. While the elongation defect is suppressed by glycerol or dimethylsulfoxide, the initiation defect is not. Possible roles for the beta' subunit in enzyme function are discussed in light of these results.
Mol Gen Genet 1977 Oct 20
PMID:Multiple effects of an RNA polymerase beta' mutation on in vitro transcription. 33 27


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