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Volume 49, Issue 1
Displaying 1-4 of 4 articles from this issue
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Isamu UTSUMI, Kiyoshi HARADA, Hiroshi MIURAArticle type: Article
1975 Volume 49 Issue 1 Pages 1-5
Published: January 25, 1975
Released on J-STAGE: March 02, 2018
JOURNAL FREE ACCESSThe effect of cobalamins on the oxidation of ascorbic acid (AsA) was investigated. When 20 μmol of AsA was incubated with 0.1 μmol of aquocobalamin (OH-B_<12>) in acetate buffer (pH 5) under aerobic conditions at 37℃ for 1 h, about 12 μmol of AsA was oxidized to dehydroascorbic acid. The amount of oxygen consumed to oxidize 1 mol of AsA was found to be 0.67 mol. The spectrophotometric investigation indicated that reduced cobalamin, B_<12r>, is formed as a catalytic intermediate in the oxidation of AsA. From these results, it was concluded that the oxidation of AsA is catalyzed by traces of OH-B_<12>. The catalytic activity of cobalamin analogs decreased in the order of OH-B_<12>, hydroxocobinamide > DBCC > cyanocobalamin, cyanocobinamide. The mechanism of the catalytic reaction was discussed.View full abstractDownload PDF (457K) -
Hiroshi MIURA, Kazuo MURATAArticle type: Article
1975 Volume 49 Issue 1 Pages 7-11
Published: January 25, 1975
Released on J-STAGE: March 02, 2018
JOURNAL FREE ACCESSThe effect of aquocobalamin (OH-B_<12>) on the oxidation of various biological materials was investigated. When catechols such as 3,4-dihydroxyphenylalanine (DOPA), pyrocatechol and adrenaline were incubated with OH-B_<12> in phosphate buffer (pH 7) under aerobic conditions at 37℃, oxygen consumption was observed. It was also found that OH-B_<12> accelerates the oxidation of linoleic acid, α-tocopherol and sulfite. In the oxidation of DOPA and linoleic acid, reaction products and reaction mechanisms were discussed.View full abstractDownload PDF (433K) -
Shoichi MASUSHIGE, Kyoichi TSUCHIYA, Koichi NAKAMURA, Takao SUZUKIArticle type: Article
1975 Volume 49 Issue 1 Pages 13-18
Published: January 25, 1975
Released on J-STAGE: March 02, 2018
JOURNAL FREE ACCESSThe effects of riboflavin (B_2), inosine (HxR) and some dietary conditions on xanthine dehydrogenase (XDH) activity in chick liver were studied by various combinations of these factors. Three kinds of diet, casein diet, gluten diet and B_2 free diet, were provided. The results were summarized as follows. (1) The XDH activity always increased by oral administration of HxR in every experiment. FAD content of liver also increased by administration of HxR. (2) The XDH activity in case of casein diet was slightly high when compared with gluten diet. (3) In case of B_2-deficiency, the administration of B_2 on the increase of the XDH activity was significantly effective, but the increase in amount of B_2 administration was no effect. (4) The administration of puromycin inhibited the effect of HxR on the increase of the XDH activity.View full abstractDownload PDF (632K) -
Yukio UCHIDA, Mitsunori HAYASHI, Tadashi KAMIKUBOArticle type: Article
1975 Volume 49 Issue 1 Pages 19-24
Published: January 25, 1975
Released on J-STAGE: March 02, 2018
JOURNAL FREE ACCESSComparative study was made on the affinity to glutamate mutase of cobamide coenzyme analogues containing several purine derivatives. Glutamate mutase was partially purified from the cultures of Clostridium tetanomorphum. Purinylcobamide coenzyme (PCC), 2-chloroadenylcobamide coenzyme (CACC), 2-thioadenylcobamide coenzyme (TACC) and 6-methylmercaptopurinylcobamide coenzyme (MPCC) were prepared from the cells of Propionibacterium arabinosum incubated with the respective purine derivatives. The Michaelis constants of cobamide coenzymes tested in the anaerobic glutamate mutase reaction based on the conversion of β-methylaspartic acid to glutamic acid were determined by microbiological assay method for glutamic acid formed. The K_m values of PCC, CACC, TACC, MPCC and cobalamin coenzyme were 11.6×10^<-7>, 2.3×10^<-7>, 5.9×10^<-7>, 10.9×10^<-7> and 9.3×10^<-7>M, respectively. Little or no difference was observed in V_<max> values among the cobamide coenzymes tested. The finding suggests that the kind of base, a lower ligand in vitamin B_<12> molecule, may play some role in the binding affinity of vitamin B_<12> to the apoenzyme, but there may be no special tendency in purine bases as compared with benzimidazoles.View full abstractDownload PDF (634K)
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