1999 Fiscal Year Final Research Report Summary
A hemoglobin-like protein in ciliated protozoa : Its structure, function and molecular evolution
| Project/Area Number |
10440248
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
動物生理・代謝
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| Research Institution | HIROSAKI UNIVERSITY (1999)
Tohoku University (1998) |
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Principal Investigator |
SHIKAMA Keiji Hirosaki Univ., Faculty of Education, Professor, 教育学部, 教授 (40004337)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUIOKA Ariki Tohoku Univ., Grad. Schl. of Sci., Research Assistant, 大学院・理学研究科, 助手 (30222293)
MURAKAMI Osamu Hirosaki Univ., Faculty of Education, Professor, 教育学部, 教授 (60006088)
WATANABE Tsuyoshi Tohoku Univ., Grad. Schl. of Sci., Professor, 大学院・理学研究科, 教授 (20027494)
TAJIMA Gen-ichi Tohoku Univ., Grad. Schl. of Sci., Research Assistant, 大学院・理学研究科, 助手 (00197360)
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| Project Period (FY) |
1998 – 1999
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| Keywords | hemoglobin / myoglobin / Tetrahymena / Paramecium / autoxidation / molecular evolution / ciliate / intron |
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| Research Abstract |
A myogobin-like protein isolated from Tetrahymena pyriformis is composed of 121 amino acid residues. This is much smaller than sperm whale myoglobin by 32 residues, suggesting a distinct origin from the common globin. We have therefore examined this unique protein for its spectral and stability properties. As a result, the rate of autoxidation of Tetrahymena oxymyoglobin was found to be almost comparable to that of sperm whale MbO2 over a wide range of pH 4 - 12 in 0.1 M buffer at 25℃. Moreover, both pH-profiles exhibited the proton-assisted process performed by the distal histidine as its catalytic residue. These kinetic observations are in full accord with spectral examinations for the presence of a distal histidine in ciliated protozoa myoglobins. At the same time, we have isolated the globin genes from Tetrahymena pyriformis and T. thermophila, and found that there is no intron in their genomic structures. This is in a sharp contrast to previous literatures on the same types of the contracted or truncated globin genes from Paramecium caudatum and Chlamydomonas eugametos. Rather, the Tetrahymena genes seemed to be closely related to the cyanobacterial globin gene derived from Nostoc commune. In fact, the comparison of these ancient globins show a marked diversity not only in the genomic DNA pattern but also in the protein structure.
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Research Products
(14 results)
