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At least 1,603 records · Page 89Linked to original sources
PubMed1983

Reversal of growth inhibition in Escherichia coli by bisulfite.

Bisulfite inhibits growth, protein synthesis and RNA synthesis in micro-organisms. These inhibitory effects, in Escherichia coli K12, were diminished when certain amino acids were added to the minimal growth medium. The effects of individual amino acids were additive, synergistic and independent of their concentration. At 10 or 5 mM bisulfite, the presence of tyrosine had the greatest importance, while phenylalanine, glycine and methionine played a lesser role. E. coli cultures resume growth subsequent to bisulfite inhibition, after a lag whose duration is proportional to the initial concentration of added bisulfite. This resumption of growth was shown not to result from the depletion of bisulfite (by air oxidation or metabolism), but rather to adaptation to the presence of bisulfite concentrations that previously were inhibitory. The inhibitory effects of bisulfite were duplicated by lesser concentrations of cysteine. Both substances inhibited RNA synthesis by a mechanism that was independent of the stringent control system. A sulfite reductase deficient mutant was more resistant to inhibition by both bisulfite and cysteine. The various results indicate that growth inhibition by bisulfite is not due to covalent reactions with cellular target molecules, but to conversion of bisulfite to other substances, probably including cysteine, which in turn inhibit bacterial growth.

Amino Acids↗
PubMed1978

A new variant of methylmalonic acidemia-defective coenzyme-apoenzyme binding in cultured fibroblasts.

Cultured fibroblasts from a patient with methylmalonic acidemia, clinically responsive to vitamin B-12, were studied in vitro. Kinetic analysis revealed abnormal binding of the coenzyme, 5'-deoxyadenosylcobalamin, for its methylmalonyl-CoA carbonylmutase apoenzyme, i.e., KM of 3.8 X 10(-5) M versus control KM of 1.5 X 10(-8) M. These data are interpreted as indicating a structural defect of the apoenzyme at the coenzyme binding site, and represent another variant of this genetic disorder.

Amino Acid Metabolism, Inborn Errors↗
PubMed1980

Tissue levels of glycolytic enzymes in phosphoglycerate kinase deficiency.

Phosphoglycerate kinase deficiency is a rate, X-linked disorder associated with a severe haemolytic anaemia. In general the deficiency has been demonstrated only in erythrocytes and leucocytes. However, in a subject with this condition, the activity of phosphoglycerate kinase in lymphocytes and platelets was also shown to be less than 5% of the normal value. Following the death of this subject in 1979, the deficiency was also found to occur in tissue samples of brain, skeletal muscle, liver and cardiac muscle, obtained at the autopsy. Values for phosphoglycerate kinase were of the order of 0.5-5% of normal controls. Other glycolytic enzymes which were tested were hexokinase, pyruvate kinase, enolase and 2-phosphoglyceromutase. In general, values for these enzymes were either normal or slightly raised.

Adolescent↗
PubMed1986

Hypoxic incubation leads to concerted changes of carbonic anhydrase activity and 2.3 DPG concentration of chick embryo red cells.

Red cell carbonic anhydrase activity, 2.3 DPG concentration, and activities of three key enzymes controlling DPG metabolism (PK, PFK and DPGM) were measured in normoxic and hypoxic (incubation in 13.5% O2) chick embryos. In normoxia 2.3 DPG concentration and carbonic anhydrase activity begin to increase by the third week of incubation. Hypoxia induces a rise of 2.3 DPG concentration and carbonic anhydrase activity by Day 8 of development, i.e., 1 week earlier. Since during normal development chick embryos become hypoxic in the third week of incubation, the results suggest that PO2 has a controlling influence on the timing of differentiation events of definitive embryonic red cells.

Animals↗
PubMed1989

Metabolic regulation during early frog development: glycogenic flux in Xenopus oocytes, eggs, and embryos.

32P-labeled glucose 6-phosphate and phosphoenolpyruvate were injected into oocytes, fertilized eggs, and early embryos of Xenopus laevis, and the 32P label was followed into glycolytic enzymes and acid-soluble metabolites. The kinetics of labeling of phosphoglucomutase and phosphoglyceromutase and the formation of specific metabolites were used to measure carbon flux through glycolytic intermediates in these cells. In full-grown stage VI oocytes, fertilized eggs, and cells of cleaving embryos, carbon metabolism is in the glycogenic direction. Glycolytic intermediates injected into these cells were metabolized into UDP-glucose and then presumably into glycogen. Carbon flow between phosphoenolpyruvate and glucose 6-phosphate does not utilize fructose 1,6-bisphosphatase; rather, it may depend largely on enzymes of the pentose phosphate pathway. Maturation and fertilization of the oocyte did not result in a change in the qualitative pattern of metabolites formed. Pyruvate kinase, although abundant in oocytes and embryos, is essentially inactive in these cells. Pyruvate kinase also appears to be inactive in small previtellogenic stage II oocytes; however, in these cells injected glycolytic intermediates were not metabolized to UDP-glucose.

Animals↗
PubMed1988

The herbicidally active experimental compound Hoe 704 is a potent inhibitor of the enzyme acetolactate reductoisomerase.

Growth inhibition of plants and bacteria by the experimental herbicide Hoe 704 (2-methylphosphinoyl-2-hydroxyacetic acid) was alleviated by the addition of the branched-chain amino acids to growth media. Hoe 704 caused a massive accumulation of acetoin and acetolactate, indicating its direct interference with the branched-chain amino acid biosynthetic pathway. The second enzyme of this pathway, acetolactate reductoisomerase (EC 1.1.1.86), was found to be subject to strong inhibition by Hoe 704. The inhibition was time-dependent and competitive with the enzyme's substrate, acetolactate. This report establishes acetolactate reductoisomerase as a new target for a herbicidal compound.

2-Acetolactate Mutase↗
PubMed1994

Biochemical characterization of human erythrocytes fractionated by counter-current distribution in aqueous polymer two-phase systems.

The fractionation of normal human erythrocytes by counter-current distribution (CCD) in charge-sensitive dextran-polyethylene glycol two-phase systems was confirmed and extended to red blood cells from heterozygous beta-thalassaemic patients. The differences between the distribution profiles of normal (homogeneous) and abnormal (heterogeneous) red blood cells reflect their different surface-charge properties. As suggested by the decline of membrane sialic acid released after neuraminidase treatment and the specific activities of two age-dependent enzymes (membrane acetylcholinesterase and intracellular pyruvate kinase) in the distribution profiles (from the left- to the right-hand side fractions), the fractionation seems to be according to red blood cell age. A constancy of the 2,3-bisphosphoglycerate level was observed in ageing red blood cells.

2,3-Diphosphoglycerate↗