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Biomedical subjects

K Hiwada

Publications and source records attributed to K Hiwada.

At least 415 records · Page 23Linked to original sources
PubMed1975

Effects of unilateral nephrectomy on plasma renin substrate and renin concentration in rats.

Effects of unilateral nephrectomy on plasma renin concentration and renin substrate (angiotensinogen) concentration were studied over an experimental period of 10 days in rats. The maximum increase in plasma renin substrate concentration after bilateral nephrectomy was 9 times higher than the preoperative level. Very low but measureable plasma renin concentrations were found in rats nephrectomized bilaterally 24 hrs previously. In unilateral nephrectomized rats the concentration of renin substrate in plasma increased maximumly 3.5-fold within 24 hrs after the operation and on the third day it was decreased to half of the maximum level. Even 10 days after uninephrectomy the concentration of plasma renin substrate was significantly higher than that of normal rats. Twenty four hours after unilateral nephrectomy plasma renin concentration decreased to similar low levels as those found in bilateral nephrectomized rats. The decreased concentration of plasma renin, however, returned to normal 3 days after uninephrectomy. The inverse relationship was seen between the concentrations of plasma renin and plasma renin substrate. However, substrate concentration in plasma rised faster and longer than plasma renin decreased.

Angiotensin II↗
PubMed1974

Alkaline phosphatase from pig kidney. Method of purification and molecular properties.

Alkaline phosphatase (EC 3.1.3.1) from pig kidney brush-border membranes was solubilized from membrane precipitates by butan-1-ol at a critical pH of 7.0. The 12000-fold purification procedure included (NH(4))(2)SO(4) precipitation, DEAE-and TEAE-cellulose chromatography, Sephadex G-200 gel filtration and neuraminidase digestion followed by DEAE-cellulose chromatography. The purified protein contained 20% (w/w) carbohydrate and had mol.wt. 150000-156000 as estimated by Sephadex filtration and ultracentrifuge analysis. It was a tetrameric glycoprotein consisting of identical subunits, and it had a molecular activity at 25 degrees C of 2600s(-1) per tetramer. Its concentration in kidney was estimated to be 8.5-8.8mg/kg.

Alkaline Phosphatase↗
PubMed1974

Catalytic properties of alkaline phosphatase from pig kidney.

The enzymic properties of alkaline phosphatase (EC 3.1.3.1) from pig kidney brush-border membranes were studied. 1. It hydrolyses ortho- and pyro-phosphate esters, the rate limiting step (V(max.)) being independent of the substrate. It transphosphorylates to Tris at concentrations above 0.1m-Tris. 2. The pH optimum for hydrolysis was between 9.8 and 10. The pK of the enzyme-substrate complex is 8.7 for p-nitrophenyl phosphate and beta-glycerophosphate. Excess of substrate inhibits the enzymic activity with decreasing pH. The pK of the substrate-inhibited enzyme-substrate complex, 8.7, is very similar to that for the enzyme-substrate complex. The pK values of the free enzyme appear to be 8.7 and 7.9. 3. Inactivation studies suggest that there is an essential tyrosine residue at the active centre of the enzyme. 4. The energy of activation (E) and the heat of activation (DeltaH) at pH9.5 showed a transition at 24.8 degrees C that was unaffected by Mg(2+). 5. Kinetic and atomic-absorption analysis indicated the essential role of two Zn(2+) ions/tetrameric enzyme for an ordered association of the monomers. Zn(2+) in excess and other bivalent ions compete for a second site with Mg(2+). Mg(2+) enhances only the rate-limiting step of substrate hydrolysis. 6. Amino acid inhibition studies classified the pig kidney enzyme as an intermediate type of previously described alkaline phosphatases. It has more similarity with the enzyme from liver and bone than with that from placenta.

Alkaline Phosphatase↗
PubMed1974

Alkaline phosphatase from pig kidney. Microheterogeneity and the role of neuraminic acid.

Several alkaline phosphatases (EC 3.1.3.1) could be obtained from pig kidney brush-border membrane on extraction with butan-1-ol. Three of the multiple forms were separated by DEAE-cellulose chromatography and further purified. They form a regular series with different degrees of glycosylation (mainly owing to N-acetylneuraminic acid), of charge, of molecular weight, of stability to temperature, to pH and to urea, of minimal requirement for Mg(2+) and of extractability by butan-1-ol. In contrast, the detectable antigenic sites, the inhibition by amino acids and the pH-dependency of K(m) and V(max.) were identical for these multiple forms. On treatment with neuraminidase, the multiple forms became identical in all their properties. It was therefore concluded that the microheterogeneity of alkaline phosphatase is due to different degrees of glycosylation at polypeptide chains which appear to be otherwise identical.

Alkaline Phosphatase↗