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

This is the second of a series of four articles in which the chemical, enzymological and crystallographic work on Ribonucleate (deoxyribonucleate)-3'-nucleotidohydrolase, EC 3.1.4.4. (staphylococcal nuclease, micrococcal nuclease) will be reviewed and correlated. This article discusses studies in solution delineating the extent of the binding site of the enzyme and identifying some of the particular amino acid residues that form this site. In addition, the effects of the very potent inhibitory combination of thymidine-3',5'-diphosphate and Ca2+ on the conformation of the enzyme and its physical, chemical and enzymological properties will be reviewed.
Mol Cell Biochem 1979 Jan 15
PMID:Staphylococcal nuclease reviewed: a prototypic study in contemporary enzymology. II. Solution studies of the nucleotide binding site and the effects of nucleotide binding. 42 93

In order to study the control of vasopressin-release, the effect of a series of potential agents was studied in an in vitro perifusion system of rat neurohypophysis after in vivo treatment with nialamide, a monoamine oxidase inhibitor. In this system, metlatonin stimulated vasopressin-release in a dose-dependent manner (1 x 10-8 to 1 x 10-3 M). Serotonin (1 x 10-3 M) also led to a significant increase of vasopressin-release whereas quipazine (1 x 10-3 M), a putative serotonin agonist and monoamine oxidase inhibitor, caused a 3-fold stimulation of the release of the neurohormone. The stimulatory effects of melatonin and serotonin were prevented by omission of Ca2+ combined to an excess of Mg2+ (12mM) in the perifusion medium. 1 x 10-6 M somatostatin did not affect basal or melatonin-stimulated vasopressin-release. These results show that melatonin and serotonin can have a direct stimulatory effect on vasopressin release at the neurohypophyseal level.
Mol Cell Endocrinol 1979 May
PMID:Melatonin-and serotonin-stimulated release of vasopressin from rat neurohypophysis in vitro. 46 80

Removal of the thyroid in normocalcemic rats with functional parathyroid transplants was found to reduce the hepatocyte DNA synthetic activity which normally follows partial hepatectomy. This proliferative incapacitation of hepatocytes appeared to be due specifically to a calcitonin deficiency since it was overcome by a single injection of pure synthetic salmon calcitonin shortly after partial hepatectomy. Salmon calcitonin and bovine parathyroid hormone were equally able to reverse the similar proliferative incapacitation of hepatocytes in hypocalcemic rats which had both their parathyroid and thyroid glands removed one day before partial hepatectomy. However, these two hormones (individually or together) could not reverse the proliferative incapacity resulting from a more prolonged (3-day) exposure to the hypocalcemic conditions in thyroparathyroidectomized rats, but the proliferative incapacity could be reversed by simultaneous treatment with the vitamin D3 metabolite, 1 alpha,25-dihydroxycholecalciferol. We suggest that extracellular calcium ions are the actual regulators of this hormonally-controlled hepatocyte proliferative development and that parathyroid hormone and the vitamin D3 metabolite affect proliferation indirectly by determining the extracellular calcium concentration, while calcitonin directly, or indirectly, sensitizes hepatocytes to the action of calcium.
Mol Cell Endocrinol 1979 Aug
PMID:The control of liver regeneration by calcitonin, parathyroid hormone and 1 alpha,25-dihydroxycholecalciferol. 49 50

A method, using albumin-pyrene complexes, has been developed for labeling, in a controlled manner, crab leg nerves whose excitability was preserved. The excimer-to-monomer fluorescence intensity ratio of pyrene, embedded in nerve membrane lipids and in their crude lipid extracts, is a fluidity parameter which displayed the following features with temperatures. a--a temperature-dependent increase of fluidity b--three breaks (6 degrees, 19 degrees and 37 degrees C) in the physiological medium c--In Ca++-depleted sea water, the 37 degrees characteristic temperature vanished. These breaks may reflect some lateral phase separations of the lipid components of nerve membranes. The calcium dependent temperature break may involve a segregation of acidic phospholipids while the other two breaks (6 degrees and 19 degrees C) may be due to neutral lipids phase separation. The relationship of these findings to nerve function is discussed.
Mol Cell Biochem 1979 Nov 01
PMID:Temperature dependence of the fluorescence of pyrene labeled crab nerve membranes. 51 67

The chemical reactivity of several minerals thought to be present in Martian fines is tested with respect to gases known in the Martian atmosphere. In these experiments, liquid water is excluded from the system, environmental temperatures are maintained below 0 degrees C, and the solar illumination spectrum is stimulated in the visible and UV using a Xenon arc lamp. Reactions are detected by mass spectrometric analysis of the gas phase over solid samples. No reactions were detected for Mars nominal gas over sulfates, nitrates, chloride, nontronite clay, or magnetitie. Oxidation was not observed for basaltic glass, nontronite, and magnetite. However, experiments incorporating SO2 gas--an expected product of volcanism and intrusive volatile release--gave positive results. Displacement of CO2 by SO2 occurred in all four carbonates tested. These reactions are catalyzed by irradiation with the solar simulator. A calcium nitrate hydrate released NO2 in the presence of SO2. These results have implications for cycling of atmospheric CO2, H2O, and N2 through the regolith.
J Mol Evol 1979 Dec
PMID:Heterogeneous phase reactions of Martian volatiles with putative regolith minerals. 52 62

Duodenal tissue from chicken embryos (19 days in ovo) has been maintained in organ culture for 48 hours. The incubation medium and culture conditions were chosen to produce a linear relationship between calcium binding protein production and the logarithm of the dose of vitamin D3 steroid in the medium. The dose-response curves are parallel for vitamin D3 and both its major metabolites, 25-hydroxyvitamin D3 and 1,25-dihydroxyVITAMIN D3. The minimum concentration of 1,25-dihydroxyvitamin D3 capable of inducing calcium-binding-protein synthesis was 1 X 10(-9) M.
Mol Cell Endocrinol 1977 Mar
PMID:An in vitro bioassay for 1,25-dihydroxyvitamin D3 and other antirachitic agents. 55 22

1. Chromatography measurements indicated that adult rats converted 25-hydroxycholecalciferol into 1,25-dihydroxycholecalciferol at a lower rate than that reported earlier for young animals. In serum, less-polar metabolites were found which probably represented vitamin D esters and vitamin D3. 2. A low dietary intake of calcium resulted in an evident increase in the fraction corresponding to 1,25-dihydroxycholecalciferol in the kidneys and also in the intestinal mucosa and serum. 3. Inclusion of 0.67 mmol of cadmium/l of drinking water at a low dietary intake of calcium resulted in an increased accumulation of both cadmium and zinc in the kidneys and liver compared with values at a normal dietary calcium intake. 4. At a normal dietary calcium intake, cadmium exposure caused inhibited production of 1,25-dihydroxycholecalciferol by the kidneys and an increased accumulation of 24,25-dihydroxycholecalciferol, vitamin D3 and vitamin D esters in the serum. 5. The inhibitory effect of cadmium on the renal conversion of 25-hydroxycholecalciferol into 1,25-dihydroxycholecalciferol was almost completely counteracted by a simultaneous low dietary calcium intake. Cadmium-exposed, calcium-deficient animals also showed a maintained accumulation of 1,25-dihydroxycholecalciferol in the intestinal mucosa.
Clin Sci Mol Med 1977 Nov
PMID:Vitamin D metabolism in adult rats at low and normal calcium intake and the effect of cadmium exposure. 58 28

Carp parvalbumin has two calcium-binding domains with a similar three-dimensional structure. Using the tryptic hydrolysis at the arginine residue in position 75, it was possible to split off one calcium-binding domain. All lysine residues were protected by maleic groups which were removed at the final stage. The domain (with a peptide thirty-three residues) isolated by ion-exchange chromatography and gel filtration does not have a secondary structure in a solution and is unable to bind calcium.
Mol Biol (Mosk)
PMID:[Isolation of the calcium-binding domain of carp parvalbumin]. 61 24

1. A large-volume scintillation counter was used to measure calcium absorption from the ratio of forearm uptake of 47Ca after oral 47CaCl2 (administered with milk) to forearm uptake after intravenously administered 47CaCl2. 2. In some subjects serial measurements of both forearm uptake of 47Ca and blood 47Ca radioactivity were also recorded, and by using deconvolution both total calcium absorption and calcium absorption rate were determined. 3. The forearm ratio determination of 47Ca absorption correlated well with that obtained by deconvolution of either serial blood 47Ca or forearm 47Ca measurements provided that the forearm radioactivity measurements were made at least 8 h after the administration of 47CaCL2. 4. Although the two deconvolution techniques gave similar estimates of total calcium absorption there were discrepancies between their measurements of calcium absorption rate. These discrepancies were reduced but not eliminated by the use of additional lead shielding around the Armac counter.
Clin Sci Mol Med 1978 Jan
PMID:The measurement of calcium absorption and absorption rate with an external arm radioactivity counter. 62 Apr 99

1. Three groups of 10-days-old chicks were fed on one of three diets having phosphorus contents of 0.08 mol/kg, 0.14 mol/kg or 0.21 mol/kg. Ten days later duodenal calcium absorption by the ligated loop technique in vivo, and plasma calcium and phosphorus concentrations, were measured. In addition the metabolism in vitro of 25-hydroxycholecalciferol [25-(OH)D3] by kidney homogenates was studied. 2. In the low phosphorus group (0.08 mol/kg) calcium absorption and the activity of 25-(OH)D3-1-hydroxylase were significantly higher than those of the high phosphorus group (0.21 mol/kg). However, in the medium phosphorus group (0.14 mol/kg), calcium absorption was significantly higher although the activity of 25-(OH)D3-1-hydroxylase was not significantly higher when compared with the high phosphorus group (0.21 mol/kg). 3. It is concluded that in phosphorus deprivation, unlike in calcium deprivation, a diet very low in phosphorus is required to stimulate the renal 25-(OH)D3-1-hydroxylase activity.
Clin Sci Mol Med 1978 Feb
PMID:Metabolism in vitro of 25-hydroxycholecalciferol in chicks fed on phosphorus-deficient diets. 62 May 6


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