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Biomedical subjects

T Kokubu

Publications and source records attributed to T Kokubu.

At least 199 records · Page 11Linked to original sources
PubMed1978

Membrane-bound arylamidase from human hepatoma cells having the same electrophoretic mobility as placental membrane-bound arylamidase.

A membrane-bound arylamidase from well-differentiated hepatocellular carcinoma having the same electrophoretic mobility as placental membrane-bound arylamidase was found. The enzyme was found to be a sialoprotein and was activated by Co2+. Hepatoma membrane-bound arylamidase had a similar molecular weight (240 000) and kinetic properties to normal liver membrane-bound arylamidase, but differed from the liver enzyme with respect to electrophoretic mobility, heat stability and urea inactivation.

Aminopeptidases↗
PubMed1977

Comparison of soluble and membrane-bound neutral arylamidases from renal cell carcinoma.

Soluble and membrane-bound neutral arylamidases from renal cell carcinoma were partially purified and their properties were compared. Soluble neutral arylamidase was a heat labile and SH-dependent metalloenzyme. Membrane-bound neutral arylamidase was a rather heat stable metalloenzyme and was activated by Co2+ with changing KM and VMAX. KM values for soluble and membrane-bound neutral arylamidases were different. L-Methionine (5mM) did not affect the enzymic activity of soluble neutral arylamidase, but inhibited 82 percent of the enzymic activity of membrane-bound neutral arylamidase. Molecular weights of soluble and membrane-bound neutral arylamidases by Sephadex G-200 gel filtration were 140000 and 240000, respectively. Soluble and membrane-bound neutral arylamidases from renal cell carcinoma appear to be distinct enzymes.

Adenocarcinoma↗
PubMed1977

Placental form of membrane-bound neutral arylamidase found in renal cell carcinoma.

A placental form of membrane-bound neutral arylamidase was found in the tissue of renal cell carcinoma. Membrane-bound neutral arylamidases from renal cell carcinoma, an intact part of the same kidney and placenta, had the same molecular weight (240 000) and were identical with respect to KM value and effect of inhibition by chelators or amino acids. Membrane-bound neutral arylamidase from renal carcinoma had the same electrophoretic mobility and heat stability as placental membrane-bound neutral arylamidase, but differed from kidney membrane-bound neutral arylamidase with respect to electrophoretic mobility, heat stability and susceptibility to urea inactivation. Results suggest the carcinoplacental alterations in membrane-bound neutral arylamidase isoenzyme in renal cell carcinoma.

Adenocarcinoma↗
PubMed1977

Purification of angiotensin I-converting enzyme from human lung.

Angiotensin I-converting enzyme (peptidyl dipeptide hydrolase, EC 3.4.15.1) was solubilized from the membrane fraction of human lung using trypsin treatment and purfied using columns of DE 52-cellulose, hydroxyapatite and Sephadex G-200. The purified enzyme was shown to convert angiotensin I to angiotensin II and also to inactivate bradykinin. The specific activity of the enzyme was 9.5 units/mg protein for Hippuryl-His-Leu-OH and 0.665 mumol/min per mg protein for angiotensin I. The enzymic activity obtained after trypsin treatment (1 mg/200 mg protein) for 2 h could be divided into three components: (i) an enzyme of molecular weight 290 000 (peak I), (ii) an enzyme of molecular weight 180 000 (peak II) and (iii) an enzyme of molecular weight 98 000 (peak III), by columns of DE 52-cellulose and Sephadex G-200. Km values of peak I, II and III fraction for Hippuryl-His-Leu-OH were identical at 1.1 mM. pH optimum of the enzyme was 8.3 for Hippuryl-His-Leu-OH.

Angiotensin II↗
PubMed1977

Comparison of human membrane-bound neutral arylamidases from small intestine, lung, kidney, liver and placenta.

Human membrane-bound neutral arylamidases were solubilized from small intestinal mucosa, lung, kidney, liver and placenta with trypsin. These five membrane-bound neutral arylamidases were identified by polyacrylamide gel-disc electrophoresis. The heat sensitivity of each enzyme was in the order, liver and placenta greater than kidney greater than lung greater than small intestine. This order correlates with that of electrophoretic mobility, except for the placental membrane-bound neutral arylamidase. Five membrane-bound neutral arylamidases have the same molecular weight, 240 000, as estimated by Sephadex G-200 gel filtration. The five membrane-bound neutral arylamidase have very similar KM values (8.7 x 10(-5) M towards L-alanyl-beta-naphthylamide), optimal pH values, hydrolysis ratios towards L-alanyl-beta-naphthylamide and L-leucyl-beta-naphthylamide, and sensitivities of inhibition by chelators or amino acids. These results suggest that the multiple forms of membrane-bound neutral arylamidase found in five different human organs are organ-specific isoenzymes.

Amino Acids↗
PubMed1977

Neutral arylamidase in urine of healthy and nephrotic children.

The neutral arylamidase activity in urine of healthy and nephrotic children was determined using L-leucyl-beta-napthylamide as substrate. The neutral arylamidase activity in urine samples from 13 nephrotic children (22.4+/-3.0 (S.E.) mumol/min/g of creatinine) was significantly higher (p less than 0.001) than that from 27 normal children (8.5+/-0.4). Two forms of neutral arylamidase were demonstrated by polyacrylamide gel electrophoresis and Sephadex G-200 gel filtration in urine samples from normal children. One was a high molecular weight arylamidase (more than 1 000 000), the other had a molecular weitht of 240 000 as estimated by Sephadex G-200 gel filtration. Two additional electrophoretically distinct froms of neurtral arylamidase were demonstrated on polyacrylamide gel in urine samples from nephrotic children. Two neutral arylamidases from normal children, one additional arylamidase from normal children, one additional arylamidase from nephrotic children and kidney membrane-bound neurtral arylamidase had identical KM values, effect of inhibition by L-methionine and heat stability. One of four urinary arylamidases from nephrotic children was suggested to be derived from plasma. It is concluded that an increase in urinary neutral arylamidase activity in nephrotic children is not only due to increased released from kidney membranes, but also due to leakage of plasma neutral arylamidase in the urine.

Adolescent↗
PubMed1977

Separation of human renin substrate from renin and a major contaminating albumin using a concanavalin A-sepharose column.

Human plasma renin substrate was purified and separated from renin by a concanavalin A-Sepharose affinity column. Human renin substrate as well as renin were bound to concanavalin A. Renin substrate was eluted with 0.1 M D-glucose in 20 mM Tris/HCl buffer, pH 8.0. The specific activity increased from 38.5 to 653 ng of angiotensin-I equivalents per mg of protein (17-fold) and the recovery was 85%. Renin was eluted completely with 0.2 M alpha-D-methylglucoside and 0.2 M alpha-D-methylmannoside.

Angiotensin II↗