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Silk fibroin with the alanyl carboxyl carbon enriched with 13C was obtained by giving a diet containing 13C-enriched alanine to the larvae of Bombyx mori and Antheraea pernyi at the fifth instar. Sericin-free fibroin fibers were prepared from cocoons, and gut was made from the liquid silk in the gland. The final 13C content was about 13%. Cross polarization/magic angle sample spinning spectra at 25 MHz and 75 MHz were measured for each sample at different orientations. Spectra were simulated using the principal values and orientations of the shielding tensor in the alanine crystal. The results indicate that the beta-structure of the fibroin may be a little more flattened than the typical pleated sheet beta-structure. 相似文献
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Ono Mayumi Kuwano Michihiko Mizushima Shoji 《Molecular genetics and genomics : MGG》1979,170(1):11-23
Molecular Genetics and Genomics - Ribosomal protein S1 from a newly isolated Escherichia coli mutant has a molecular weight of about 54,000 which is smaller than the wild type S1 (M.W. 65,000). The... 相似文献
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Keisuke Hanaki Tomonori Matsuo Michihiko Nagase 《Biotechnology and bioengineering》1981,23(7):1591-1610
The inhibitory effect of long-chain fatty acids on the anaerobic digestion process was examined in batch experiments using synthetic substrates. The addition of long-chain fatty acids caused the appearance of the appearance of the lag period in the methane production from acetate and in the degradation of both long-chain fatty acids and n-butyrate. Methane production from hydrogen proceeded without lag period although its rate was lowered. Fermentation of glucose was not inhibited. Neutral fat in the whole milk was easily hydrolyzed to long-chain fatty acids, which brought about the inhibition. The addition of calcium chloride reduced the inhibitory effect of long-chain fatty but it did not do so after the culture had been exposed to long-chain fatty acids for more than several hours. The addition of calcium carbonate could not reduce the inhibition because of its insolubility. 相似文献
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Immunoglobulin class switch involves a unique recombination event that takes place at the region 5′ to each heavy chain constant region gene during B lymphocyte differentiation. Such regions that are responsible for the class-switch recombination are defined as S regions (Kataoka et al., Proc. Natl. Acad. Sci. USA 77, 919, 1980). We have cloned a rearranged γ2b gene from a mouse myeloma (MPC11) and compared its structure with the germ line counterparts. The rearranged γ2b gene contained the 5′ flanking region of the γ3 gene (Sγ3 region) which are linked to the 5′ flanking region of the γ2b gene (Sγ2b region). We have determined nucleotide sequences surrounding the recombination site of the rearranged and germ line γ2b genes, which include the Sγ2b and Sγ3 regions. Both γ2b and Sγ3 regions comprise tandem repetition of conserved units of 49 bp. Similar 49 bp repeating units are also found in the previously determined sequence of the Sγ1 region in which class-switch recombination took place in MC101 myeloma. The nucleotide sequences of the Sγ1, Sγ2b and Sγ3 repeating units share significant homology with each other. The Sμ region, partial nucleotide sequence of which was previously determined, contains abundant short sequences such as AGCT, TGGG and AGCTGGGG which are shared in common by repeating sequences in Sγ regions. These results suggest that the recombination responsible for class switch from μ to γ or from a γ to another γ, may be facilitated directly or indirectly by homology of repeating sequences in S regions. 相似文献
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T Inoue N Nishio S Suzuki K Kataoka T Kohzuma Y Kai 《The Journal of biological chemistry》1999,274(25):17845-17852
The crystal structures of oxidized and reduced pseudoazurins from a denitrifying bacterium, Achromobacter cycloclastes IAM1013, have been determined at 1.35- and 1.6-A resolutions, respectively. The copper site in the oxidized state exhibits a distorted tetrahedral structure like those of other pseudoazurins. However, not only a small change of the copper geometry, but concerted peptide bond flips are identified. The imidazole ring of remote His6 has a hydrogen bonding distance of 2.73 A between N-delta1(His6) and O-gamma1(Thr36) in the oxidized protein. When the protein is reduced at pH 6.0, the imidazole ring rotates by 30.3 degrees and moves 1.00 A away from the position of the oxidized state. A new hydrogen bond between N-epsilon2(His6) and O-epsilon1(Glu4) is formed with a distance of 3.03 A, while the hydrogen bond between N-delta1(His6)-O-gamma1(Thr36) is maintained with an interatomic distance of 2.81 A. A concomitant peptide bond flip of main chain between Ile34 and Thr36 occurs. 相似文献
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