著者

近藤 次郎 竹中 章郎

出版者

The Crystallographic Society of Japan

雑誌

日本結晶学会誌 (ISSN:03694585)

巻号頁・発行日

vol.46, no.5, pp.345-351, 2004-10-29 (Released:2010-09-30)

参考文献数

24

被引用文献数

1

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Recent human genome projects have revealed that exons encoding proteins count only a few percents, whereas many kinds of repetitive sequences occupy more than 50 % of genome. Some of the latter are related to genetic diseases, but their biological functions and structures are still unknown. Two X-ray structures of a short DNA fragment of d (gcGA [G] 1Agc) show that four base-intercalated duplexes are assembled to form an octaplex at a low K+ concentration, in which the eight G5 residues form a stacked double G-quartet in the central part. At a higher K+ concentration, however, the octaplex is split into just two halves. These structural features suggest a folding process according to a double Greek-key motif for eight tandem repeats of d (ccGA [G] 4Agg) found in Variable number of tandem repeat (VNTR) immediately adjacent to the human pseudoautosomal telomere. Such a packaging of the repeats could facilitate slippage of a certain VNTR sequence during DNA replication, to induce length polymorphism by increasing or decreasing of the repeats.

著者

竹中 章郎

出版者

The Crystallographic Society of Japan

雑誌

日本結晶学会誌 (ISSN:03694585)

巻号頁・発行日

vol.48, no.5, pp.311-319, 2006-10-31 (Released:2010-09-30)

参考文献数

4

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As an easy technique for phase determination in X-ray analysis of macromolecular crystals, the molecular replacement method is widely used. Available computer programs are highly sophisticated to user friendly so that users can use them without knowledge on the theoretical backgrounds. To develop the technique to more powerful tool, as well as to resolve individual problems in special cases, it is essential to understand the details of the backgrounds. Here the theories of the method with the historical backgrounds, its availability and capability, practical usage and trouble shooting will be described.