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Biomedical subjects

K Konno

Publications and source records attributed to K Konno.

At least 577 records · Page 32Linked to original sources
PubMed1975

Axyl hydrocarbon hydroxylase in Morris hepatoma 5123D.

Aryl hydrocarbon hydroxylase activity in Morris hepatoma 5123D is very low, but apparently increases by the administration of 3-methylcholanthrene, as demonstrated in the host liver, small intestine, and lung from the rats bearing this tumor. The peak level of the increased activity in tumor appears 48 hr after the initial administration when the repeated treatment is given intragastrically every 24 hr. 7,8-Benzoflavone increases the enzyme activity in tumor and lung, but not in liver and small intestine. Among the subcellular fractions of the tumor cells, induction of the enzyme by 3-methylcholanthrene was observed in microsomes and nuclei, and the increased level of the activity was higher in microsomes than in nuclei.

Animals↗
PubMed1975

Properties of aryl hydrocarbon (benzo[a]pyrene) hydroxylase in the liver from C3H/He and DBA/2 strains of mice.

Aryl hydrocarbon hydroxylase activity in liver from the C3H/He strain of mice is apparently increased by the administration of 3-methylcholanthrene, but the enzyme activity from the DBA/2 strain of mice is not. The enzyme activity from female mice is higher than that from male mice, even 72 hr after a single application of 3-methylcholanthrene into the mice. The control enzyme in the liver from both strains of mice has a pH optimum at 7.9 and the induced enzyme from C3H/He mice, at 8.2. There are approximately the same levels of the apparent Km for benzo[a]pyrene, NADPH, or NADH in the liver enzyme from both strains of mice even after treatment with 3-methylcholanthrene. The induced enzyme is inhibited by 7,8- or 5,6-benzoflavone non-competitively, and nicotinamide inhibits both the constitutive and induced enzyme uncompetiviely. Cyclohexene oxide and 1,1,1-trichloropropane oxide, known to be inhbitors of epoxide hydrase, inhibit the activity of the constitutive enzyme, but enhance the induced enzyme in the liver. The difference in the properties between the constitutive and induced enzymes from mouse liver is discussed briefly.

Animals↗
PubMed1975

Aryl hydrocarbon hydroxylase in liver nuclei of C3H/He and DBA/2 mice.

Aryl hydrocarbon hydroxylase activity in liver nuclei from C3H/He mice is apparently increased by the administration of 3-methylcholanthrene, but the enzyme activity from the DBA/2 mice is not. On the other hand, by treatment of the mice with phenobarbital sodium, the increased activity in liver nuclei was observed in both strains of mice. There are approximately the same levels of the apparent Km for benzo[alpha]pyrene in liver nuclei from both strains of mice even after treatment with 3-methylcholanthrene, but different Km values for NADPH and NADH are observed between the constitutive and induced enzyme, showing 0.032 and 0.091 mM for NADPH, and 0.303 and 1.67 mM for NADH, respectively. Both 5, 6- and 7, 8-benzoflavones enhance the activity in the constitutive enzyme, but inhibit it in the induced enzyme non-competitively. Nicotinamide inhibits both enzyme activities in liver nuclei. Cyclohexene oxide and 1, 1, 1-trichloropropane oxide enhance the activity in the induced enzyme, but not in the constitutive enzyme in liver nuclei. The differences in the properties between the contitutive and induced enzymes and between the enzymes in microsomes and in nuclei from mouse liver were discussed briefly.

Animals↗
PubMed1975

Properties of aryl hydrocarbon hydroxylase in microsomes of Morris hepatoma 5123D and the host liver.

Properties of aryl hydrocarbon hydroxylase in the microsomes were compared between Morris hepatoma 5123D and the host liver from rats bearing this tumor. Requirement of NADPH for the assay of the enzyme activity was observed, compared to that of NADH, and also the additive effect of NADH on the requirement of NADPH was found in the tumor and liver. Curve of pH optimum of the enzyme activity in tumor and liver differed between the rats treated with corn oil and those with 3-methylcholanthrene, indicating a slight shift of the peak value to alkaline pH in the latter. The same values of the apparent Km for NADPH and NADH were shown for the enzyme from the liver and tumor even 24 hr after the treatment with 3-methylcholanthrene, but a difference in the apparent Km for benzo[a]pyrene was demonstrated between the tumor and the host liver, showing 3.6 approximately 6.6 muM in the former and 9.1 approximately 20 muM in the latter. By the addition of 7,8- or 5,6-benzoflavone to the assay medium for the tumor, the induced enzyme was inhibited noncompetitively, and the constitutive enzyme was enhanced, as demonstrated in the host liver. As observed in the induced enzyme in both tissues, cyclohexene oxide and 1,1,1-trichloropropane oxide slightly increased the activity of the constitutive enzyme in the tumor, in contrast to its inhibition in the host liver.

Animals↗