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Biomedical subjects

M Noshiro

Publications and source records attributed to M Noshiro.

At least 109 records · Page 6Linked to original sources
PubMed1985

Assays for cholesterol 7 alpha-hydroxylase and 12 alpha-hydroxylase using high performance liquid chromatography.

Rapid and accurate assay methods for cholesterol:NADPH oxidoreductase (EC 1.14.13.17, 7 alpha-hydroxylating) and 7 alpha-hydroxy-4-cholesten-3-one 12 alpha-hydroxylase (enzyme not yet registered) are described. 7 alpha-Hydroxylase utilizes the endogenous cholesterol of liver microsomes as substrate. The reaction products were separated by high performance liquid chromatography monitored at 214 nm. Much higher activity was obtained with the method compared to literature values, which were obtained using externally added radioactive cholesterol as the substrate. The 12 alpha-hydroxylase activity was measured using non-radioactive steroid as the substrate. The reaction products were separated by the chromatography and detected at 240 nm. Comparable activities were obtained by this method compared to those that were obtained using radioactive substrate.

Animals↗
PubMed1984

Purification of cytochrome P-450 catalyzing 25-hydroxylation of vitamin D3 from rat liver microsomes.

Cytochrome P-450 catalyzing 25-hydroxylation of cholecalciferol (cytochrome P-450 cc25 ) was purified from rat liver microsomes based on its catalytic activity at each purification step. The specific cytochrome P-450 content of the final preparation was 15.1 nmol/mg of protein. Reconstituted activity of 25-hydroxylation of cholecalciferol with the purified enzyme was 2.3 nmol/min/mg of protein, which was 4,300 times as high as that in microsomes. The minimum molecular weight of the enzyme was 50,000 based on SDS-polyacrylamide gel electrophoretogram. Amino terminal sequence of the P-450 cc25 was H2N-Met-Asp-Pro-Val-Leu-Val-. Immunochemical study showed that the purified P-450 cc25 was homogeneous and the cytochrome was immunochemically different from either cytochrome P-450(PB-1) or cytochrome P-448(MC-1).

Amino Acid Sequence↗
PubMed1984

Microsomal monooxygenase system in frog livers.

Liver microsomes prepared from four species of frog, Rana catesbeiana, Rana nigromaculata , Bufo bufo japonicus, and Xenopus laevis, contained cytochrome P-450 and showed NAD(P)H-dependent monooxygenase activities to several foreign chemical compounds tested. The oxidations of the chemical compounds by frog liver microsomes showed significant variations among frog species. The oxidation of 7-ethoxycoumarin was much faster than that by rat liver microsomes. The oxidation of benzo(a)pyrene was significantly induced by 3-methylcholanthrene administration. The monooxygenase activities of frog liver microsomes were more sensitive to cyanide inhibition than those of rat liver microsomes.

Aminopyrine↗
PubMed1981

Cytochrome b5 as electron donor for oxy-cytochrome P-450.

The steady-state concentration of the oxycomplex of microsomal cytochrome P-450 in the presence of NADPH could be elevated by increasing pH and ionic strength or by adding anti-(cytochrome b5) immunoglobulin. Low pH and low ionic strength as well as incorporation of cytochrome b5 into microsomal membranes decreased the steady-state level. Parallel to these effects, the b5 antibody monooxygenase activity at low pH and low ionic strength, but was not effective at high pH and high ionic strength. This establishes a role for cytochrome b5 in donating electrons for the reduction of oxy-cytochrome P-450 to the active oxygen complex of cytochrome P-450 but also points to large variations in the importance of this role depending on the experimental conditions, the species of P-450 involved and the substrates employed.

Animals↗