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| 1.
その他 |
その他
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櫻井, 宣彦 ; Sakurai, Nobuhiko
概要:
取得学位：博士(理学)，学位授与番号：博甲第238号，学位授与年月日：平成10年3月25日,学位授与年：1998
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| 2.
論文 |
論文
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Shimizu, Atsushi ; Samejima, Tatsuya ; Hirota, Shun ; Yamaguchi, Shotaro ; Sakurai, Nobuhiko ; Sakurai, Takeshi
概要:
金沢大学理工研究域物質化学系<br />Type III Cu ligand, His456 and His458, of Myrothecium verrucaria (MT-1) bilirubin oxidases (BO) [EC
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1.3.3.5] were doubly mutated as to Lys, Asp, and Val. In spite of perturbation of the type III Cu centers, these mutants were pale blue or colourless when isolated. However, they became intense blue on reaction with reducing agents such as dithionite, ascorbate, hexacyanoferrate(II), and octacyanotangstate(IV) under air, or with an oxidizing agent such as hexacyanoferrate(III), indicating that they are in mixed forms when expressed in Aspergillus oryzae. His456.458Lys and His456.458Asp mutated as to potential coordinating groups showed weak BO and ferroxidase activities, while His 456.458Val mutated as to non-coordinating groups showed no enzyme activity at all.
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| 3.
論文 |
論文
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Shimizu, Atsushi ; Sasaki, Takashi ; Kwon, Jung Hee ; Odaka, Akito ; Satoh, Takanori ; Sakurai, Nobuhiko ; Sakurai, Takeshi ; Yamaguchi, Shotaro ; Samejima, Tatsuya
概要:
金沢大学理工研究域物質化学系<br />In our previous paper, we reported a mutant of recombinant Myrothecium verrucaria bilirubin oxidase,
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in which the Met467 residue was replaced by Gly. This mutant displayed a remarkable reduction in enzymatic activity and an evident decrease in the intensity of the absorption band around 600 nm (type 1 charge transfer transition). In this study, we report the preparation of three Met467 mutants (Met467Gln, Met467His, and Met467Arg) and characterize their enzymatic activities, midpoint potentials, and absorption and ESR spectra. Met467His and Met467Arg show no enzymatic activity and a great reduction in the intensity of the absorption band around 600 nm. Furthermore, their ESR spectra show no type 1 copper signal, but only a type 2 copper signal; however, oxidation by ferricyanide caused the type 1 copper signal to appear. On the other hand, Met467Gln as expressed shows both type 1 and type 2 copper signals in its ESR spectrum, the type 1 copper atom parameters being very different from usual blue copper proteins but very similar to those of stellacyanin. The enzymatic activity of the Met467Gln mutant for bilirubin is quite low (0.3%), but the activity for potassium ferrocyanide is similar (130%) to that of the wild type enzyme. These results indicate that Met467 is important for characterizing the features of the type 1 copper of bilirubin oxidase.
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