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Volume 75, Issue 9
Displaying 1-4 of 4 articles from this issue
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Kanetada NAGAMINE1999 Volume 75 Issue 9 Pages 255-258
Published: 1999
Released on J-STAGE: October 17, 2006
JOURNAL FREE ACCESSA new production method of intense and bright high-energy neutrino (vμ, ve) beam is proposed based upon recent success of the ultra-slow positive muons by employing laser ionization of thermal muonium. By using these muons as an ion source, one can accelerate and storage to produce high-quality neutrino beam for exploration of the inside-nature of the earth. Some detailed estimation for the beam properties is given.View full abstractDownload PDF (1257K) -
Keri WANG, Chuji HIRUKI1999 Volume 75 Issue 9 Pages 259-262
Published: 1999
Released on J-STAGE: October 17, 2006
JOURNAL FREE ACCESSThis paper reports, for the first time, the detection of a single-base-pair mutation in a 16S rDNA fragment derived from a phytoplasma isolate by a DNA heteroduplex mobility assay (HMA). The 16S rDNA fragment was amplified from aster yellows phytoplasma isolate (AY27) by polymerase chain reaction (PCR) and digested by the restriction enzyme AluI. Following the cloning of the partial 16S rDNA fragment into a plasmid vector, the cloned fragment was subjected to mutation in vitro to yield three sets of mutants containing one-, two-, or three-base-pair substitutions. The mutated 16S rDNA fragments were amplified by PCR and analyzed by HMA. The results indicated that the DNA heteroduplexes (529bp) containing at least two-base-pair difference, i.e. a 0.4% level of divergence, were separated from DNA homoduplexes in 5% polyacrylamide gel under nondenaturing conditions. A single-base-pair substitution in a 529bp DNA fragment was differentiable by HMA when the DNA fragment containing more than two-base-pair substitutions was used as a reference.View full abstractDownload PDF (1017K) -
Hideaki KOIKE, Tsuyoshi KAWASHIMA, Masashi SUZUKI1999 Volume 75 Issue 9 Pages 263-268
Published: 1999
Released on J-STAGE: October 17, 2006
JOURNAL FREE ACCESSGenes coding for enzymes that are expected to be involved in de novo biosynthesis of nucleotides have been identified using the complete genomic DNA sequences of 7 archaebacteria. By the identified enzymes of Aeropyrum pernix, no step is expected to be mediated in the pathway leading to IMP, starting from the initial metabolic precursors, 5-phosphoribosyl-1-pyrophosphate and glutamine. Thus, an atypical pathway is needed to synthesize IMP in this archaebacterium. Of any of the 7 archaebacteria, no gene is identified to code for the enzymatic activity of synthesizing GDP from GMP. Unidentified types of enzymes are expected to mediate this and some other essential steps, whose corresponding enzymes are missing from some of the archaebacteria. The identified archaebacterial enzymes are, in general, closer to enzymes of E. coli than to those of yeast, in particular, in terms of the numbers of polypeptides composing these enzymes.View full abstractDownload PDF (4043K) -
Takuo MATSUMOTO, Takamasa NONAKA, Masayuki HASHIMOTO, Takeshi WATANABE ...1999 Volume 75 Issue 9 Pages 269-274
Published: 1999
Released on J-STAGE: October 17, 2006
JOURNAL FREE ACCESSThe mature form of chitinase Al from Bacillus circulars WL-12 (one of the family 18 glycosyl hydrolases) comprises an N-terminal catalytic domain, two fibronectin type III domains and a C-terminal chitin-binding domain. In the efforts for crystallizing each domain, combined domains and the intact mature form, we have obtained crystals of the catalytic domain which diffract to a truly atomic resolution (1.13Å). The catalytic domain consists of an (α/β)8-TIM-barrel. Two small β-domains attached on top of the TIM-barrel provide a deep cleft for substrate binding. Crystals of an inactivated (through Glu204Gln mutation) catalytic domain complexed with a heptameric N-acetyl glucosamme (7NAG (NI, NII, NIII, NIV, NV, NVI, NVII-hepta-acetyl-chitoheptaose which is a β-1, 4-linked oligosaccharide of N-acetylglucosamine with a polymerization degree of seven.), which is a true substrate) diffracted up to 1.5Å resolution. The bound 7NAG substrate showed a marked kink between the sugar units at positions -1 and +1. The proximity of Glu204 to the scissile site strongly supports the hitherto conceived notion that Glu204 plays a role of catalytic acid in the so-called“substrate-assisted catalysis”mechanism which is distinct from the general acidbase mechanism long accepted for lysozyme and related glycosyl hydrolases.View full abstractDownload PDF (4987K)
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