生物谷報(bào)道：維生素B12（鈷胺素）是已知最大的非聚合物天然產(chǎn)物之一，是惟一完全由微生物合成的一種維生素,。盡管進(jìn)行了多年研究，但科學(xué)家對(duì)該維生素的一部分的生物合成仍然很不了解?，F(xiàn)在,，研究人員終于揭示了其生物合成中的最后一個(gè)未知步驟。該研究成果發(fā)表在最新一期的《Nature》雜志上,。
研究發(fā)現(xiàn)一種被命名為BluB的物質(zhì)在維生素B12的生物合成中發(fā)揮作用,。BluB的X-射線晶體結(jié)構(gòu)已被確定。它是一種酶,，利用分子氧來(lái)分解黃素（四羥酮醇）單核苷酸共因子,，形成維生素B12的低配體。這一反應(yīng)是一例不尋常的過(guò)程,，即一種共因子在酶催化下被破壞來(lái)合成另一種共因子,。
FIGURE 1. BluB catalyses DMB production.
a, Overall scheme for DMB biosynthesis and B12 formation. The atoms converted to DMB are shown in red; the reaction catalysed by BluB is in the red box. b, HPLC traces (280 nm) of reactions containing 10 M BluB, 20 mM NADH and 100 M FMN, or lacking the indicated components. Similar conversion was observed in reactions containing NADPH instead of NADH (not shown). In the absence of NAD(P)H, trace amounts of product formed, probably through adventitious photoreduction of FMN followed by turnover in the active site. c, Calcofluor fluorescence of the bluB mutant. d, Growth of wild-type S. meliloti and the bluB mutant. e, Radio-TLC of the BluB reaction containing [32P]FMN. Arrows represent migration of standards. The same result was obtained using two additional eluant systems (data not shown).
原文出處：
Nature Volume 446 Number 7134
BluB cannibalizes flavin to form the lower ligand of vitamin B12 p449
Michiko E. Taga, Nicholas A. Larsen, Annaleise R. Howard-Jones, Christopher T. Walsh and Graham C. Walker
doi:10.1038/nature05611
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作者簡(jiǎn)介：
Graham C. Walker, Ph.D.
Dr. Walker is a professor in the Department of Biology at the Massachusetts Institute of Technology (MIT) and a director of MIT's Introductory Biology Program. He received his B.Sc. degree from Carleton University and his Ph.D. from the University of Illinois at Urbana-Champaign. In addition, he was a postdoctoral fellow at both the University of Illinois at Urbana-Champaign and the University of California–Berkeley.
Dr. Walker was recently named an American Cancer Society Research Professor. He has received several awards, including the Charles Ross Scholar Award for Cancer Research, the Arthur C. Smith Award (for contributions to undergraduate life), and the 2006 Environmental Mutagen Society Award. He has served as an editor of the Journal of Bacteriology for 16 years, finishing a 10-year term as editor-in-chief in 2001. He has also been a Sigma Xi Distinguished Visiting Professor (New Jersey Medical School) and participated in the Stone Lectureship, Pennsylvania State University. In addition, he is a fellow of the American Academy of Microbiology (1994) and serves on the editorial boards of DNA Repair, Mutation Research, and Current Opinion in Microbiology as well as on the editorial committee of the Annual Review of Microbiology.
RESEARCH ABSTRACT SUMMARY:
Graham Walker studies how cells respond to DNA damage as well as the biological interdependence of certain bacteria and plants. He will establish an education group—composed of postdoctoral fellows, graduate students, and undergraduates—to focus on curricular development, including Web-based materials, for introductory biology.
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