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)

A simple method of two-dimensional polyacrylamide gel electrophoresis is described which affords: (1) high resolution of eukaryotic ribosomal proteins; (2) good recovery of protein in the transfer from first to second dimension; and (3) characterisation of the separated proteins in terms of molecular weights and other electrophoretic properties. Using this method, we have characterised 70 proteins in rabbit reticulocyte ribosomes, 30 from the small subunit and 40 from the large subunit. The molecular weight distribution is compared with those obtained by other authors after fractionation of the proteins in two dimensions.
Mol Gen Genet 1976 Dec 31
PMID:Characterisation of eukaryotic ribosomal proteins. 0 65


J Mol Biol 1976 Dec
PMID:Flagellar transformations at alkaline pH. 1 24

Published data on adsorption and condensation of amino acids, purine and pyrimidine bases, sugars, nucleosides, and nucleotides are analyzed in connection with Bernal's hypothesis that clays and other minerals may have provided the most likely surface for adsorption and condensation of these molecules in prebiotic times. Using surface concentration and reaction rate as the main criteria for the feasibility of condensation reactions, four types of prebiotic environments were analyzed: (1) an ocean-sediment system, (2) a dehydrated lagoon bed produced by evaporation, (3) the surface of a frozen sediment, and (4) a fluctuating system where hydration (rainstorms, tidal variations, flooding) and dehysration (evaporation) take place in a cyclic manner. With the possible exception of nucleotides, low adsorption of organomonomers on sediment surfaces of a prebiotic ocean (pH 8) is expected, and significant condensation is considered unlikely. In dehydrated and frozen systems, high surface concentrations are probable and condensation is more likely. In fluctuating environments, condensation rates will be enhanced and the size distribution of the oligomers formed during dehydration may be influenced by a "redistribution mechanism" in which adsorbed oligomers and monomers are desorbed and redistributed on the solid surface during the next hydration-dehydration cycle.
J Mol Evol 1976 Dec 30
PMID:The possible role of solid surface area in condensation reactions during chemical evolution: reevaluation. 1 25

E. coli K12 was found to utilise both D-and L-stereoisomers of alanine as sole sources of carbon, nitrogen and energy for growth. This capability was absolutely dependent upon the possession of an active membrane-bound D-alanine dehydrogenase, and was lost by mutants in which the enzyme was defective. The Michaelis constant for the enzyme with D-alanine as substrate was 30 mM, and the pH optimum about 8.9. D-alanine was the most active substrate, L-alanine was inactive and several other D-amino acids were 10--50% as active as D-alanine. Oxidation of D-alanine was linked to oxygen via a cytochrome-containing respiratory chain. Synthesis of the dehydrogenase was induced 16 to 23-fold by incubation with D- or L-alanine, but only D-alanine was intrinsically active as an inducer. L-alanine was active either as a substrate or inducer only in t he presence of an uninhibited alanine racemase which converted it to the D-isomer. The map-location of their structural genes between ara and leu, together with other similarities, indicate that D-alanine dehydrogenase and the "alaninase" of Wijsman (1972a) are the same enzyme. Both D- and L-alanine were intrinsically active as inducers of alanine racemase synthesis. The synthesis of both D-alanine dehydrogenase and alanine racemase was found to be regulated by catabolite repression.
Mol Gen Genet 1976 Dec 08
PMID:Biochemical, genetic, and regulatory studies of alanine catabolism in Escherichia coli K12. 1 92

1. A Valsalva-like manoeuvre was used to elicit graded rises in total peripheral resistance (TPR) in conscious rabbits. The rises were reflex and mediated through sympathetic constrictors. Propranolol infused at different rates reaching plasma concentrations up to 240 (SEM 33) ng/ml had no effect on this reflex but reduced mean arterial pressure. However, the response was attenuated by clonidine in a dose-dependent manner. 2. Valsalva manoeuvres were used to elicit graded sympathetically mediated rises in TPR index in twenty-nine subjects with mean arterial pressure ranging from 75 to 165 mmHg. Absolute sensitivity of the constrictor response increased with rising resting TPR index, resulting in some enhancement of constrictor responses in the hypertensive subjects. It seems likely that non-autonomic factors (e.g. vessel structure) rather than hyperactive neural constrictor effects are involved in the enhanced constrictor responses in essential hypertension.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Valsalva vasoconstrictor reflex in human hypertension in after beta-adrenoreceptor blockade in conscious rabbits. 1 55

1. Activity of peripheral and central catecholaminergic neurons was studied in spontaneously hypertensive rats (SHR) and deoxycorticosterone (DOCA)-salt hypertensive rats. 2. In young SHR (4 weeks) the plasma values of bpth noradrenaline and dopamine-beta-hydroxylase activity were increased compared with those of normotensive rats of the Wistar/Kyoto strain. Total catecholamines (mostly adrenaline) were not significantly different. 3. In the adrenal glands of 2-weeks-old and 4-weeks-old SHR activities of tyrosine hydroxylase, dopamine-beta-hydroxylase, phenylethanolamine-N-methyl transferase were decreased, compared to Wistar/Kyoto rats. 4. The adrenaline-forming enzyme was elevated in the A1 and A2 regions of the brain stem of 4-weeks-old SHR and in the A1 region of adult DOCA-salt hypertensive rats. 5. In the adrenal glands of adult DOCA-salt hypertensive rats tyrosine hydroxylase activity was increased. 6. These results implicate peripheral noradrenaline-containing neurons and central adrenaline-containing neurons in the development of genetic and experimental hypertension in rats.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Peripheral and central catecholaminergic neurons in genetic and experimental hypertension in rats. 1 56

1. The presynaptic mechanisms appear to be involved in the regulation of noradrenaline release during nerve stimulation. The first one. mediated by beta-adrenoceptors, operates at low frequencies of nerve stimulation, leading to an increase in transmitter release. The second one, mediated through alpha-adrenoceptors, is triggered when higher concentrations of the transmitter are reached in the synaptic cleft, leading to inhibition of transmitter release, probably through a restriction in the availability of calcium for the secretory process. 2. It is postulated that part of the anti-hypertensive effects of drugs like clonidine, alpha-methyldopa and beta-receptor-blocking agents may be related to their long-term effects on presynaptic adrenoceptors.
Clin Sci Mol Med Suppl 1976 Dec
PMID:The role of alpha- and beta-presynaptic receptors in the regulation of noradrenaline release elicited by nerve stimulation. 1 57

1. Beta-Recptor-blocking drugs are rapidly and completely absorbed after oral administration. Systemic availability is nevertheless incomplete for propranolol, alprenolol and oxprenolol, owing to "first-pass' extraction by the liver. 2. Plasma half-life is between 2 and 4 h, except for sotalol (10-12 h). Plasma elimination of propranolol is reduced with decreased liver blood flow observed in congestive heart failure or during chronic propranolol therapy itself. 3. beta-Receptor blockade is usually achieved in these concentration ranges: propranolol and alprenolol, 50-100 ng/ml; oxprenolol, 500-1000 ng/ml; pindolol, 10-30 ng/ml; sotalol, 2-6 microng/ml. Higher concentrations are often found with high doses administered to hypertensive patients.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Pharmacokinetics of beta-receptor-blocking agents in relation to their anti-hypertensive effect. 1 58

1. Oxygen consumption and central haemodynamics were recorded at rest and during exercise in fifty-one men with essential hypertension (W.H.O. stage I) and repeated after 1 year on a single drug: alprenolol (n equals 10), atenolol (13) metoprolol (12) and timolol (16). 2. Mean arterial pressure was significantly reduced in all groups at rest (11-18%) and during exercise (5-11%). Heart rate was significantly reduced in all groups (20-28%) at rest and (17-26%) during exercise. Owing to increase in supine resting and exercise stroke volume in the alprenolol and atenolol group, cardiac index decreased less than heart rate---in contrast to the timolol group where cardiac index was decreased 26-32%. The calculated post-treatment total peripheral resistance was significantly increased at rest and during exercise in the timolol group. In the other groups the total peripheral resistance was significantly increased at rest when sitting, but not at rest when supine and during exercise. 3. It is concluded that the major haemodynamic changes induced in subjects with moderate and mild essential hypertension by these different beta-receptor blockers are the same, but that minor differences exist with respect to effect upon stroke volume and total peripheral resistance.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Haemodynamic long-term effects of beta-receptor-blocking agents in hypertension: a comparison between alprenolol, atenolol, metoprolol and timolol. 1 59

1. Immediate and long-term blood pressure-lowering activity of five beta-adrenoreceptor antagonists with different ancillary pharmacological properties were compared in a randomized double-blind placebo controlled factorial trial in twenty-five previously untreated patients with stable uncomplicated essential hypertension. 2. In doses which produced similar reductions in exercise tachycardia, all drugs exerted similar anti-hypertensive activity, which was greater on systolic than diastolic pressure and greatest during exercise. 3. These effects were maximum within an hour and lasted for over 8 h after a single oral dose. 4. Blood pressure-lowering activity, particularly the reduction in exercise systolic pressure, was significantly related to the logarithm of the dose of each drug. 5. Anti-hypertensive activity was maximally enhanced after 4 weeks of sustained treatment at any given dose. There was no short-term habituation to treatment and substitution with placebo resulted in a return of the blood pressure to pretreatment values within 4 weeks without subsequent overshoot. 6. The blood pressure-lowering activity of these drugs was predominantly related to their common property of competitive antagonism of cardiac beta-adrenoreceptors; their ancillary pharmacological properties, with the exception of intrinsic vasodilator activity, played little part in this response.
Clin Sci Mol Med Suppl 1976 Dec
PMID:Comparative anti-hypertensive effectiveness of beta-adrenoreceptor antagonists with different pharmacological properties: dose-response studies during acute and chronic administration. 1 60


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