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Identification and Characterization of an Autolysin Gene, atlA, from Streptococcus criceti
Haruki Tamura,Arisa Yamada,Hirohisa Kato 한국미생물학회 2012 The journal of microbiology Vol.50 No.5
AtlA of Streptococcus mutans is a major autolysin and belongs to glycoside hydrolase family 25 with cellosyl of Streptomyces coelicolor. The autolysin gene (atlA) encoding AtlA was identified from S. criceti. AtlA of S. criceti comprises the signal sequence in the N-terminus, the putative cell-wallbinding domain in the middle, and the catalytic domain in the C-terminus. Homology modeling analysis of the catalytic domain of AtlA showed the resemblance of the spatial arrangement of five amino acids around the predicted catalytic cavity to that of cellosyl. Recombinant AtlA and its four point mutants, D655A, D747A, W831A, and D849A,were evaluated on zymogram of S. criceti cells. Lytic activity was destroyed in the mutants D655A and D747A and diminished in the mutants W831A and D849A. These results suggest that Asp655 and Asp747 residues are critical for lytic activity and Trp831 and Asp849 residues are also associated with enzymatic activity.
Aggregation States of Polyamide 4 Thin Films under an Aqueous Environment
Shunta Tamura,Haruki Mokudai,Takashi Masaki,Norifumi L. Yamada,Hisao Matsuno,Keiji Tanaka 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Polyamide 4 (PA4) having only four carbons between neighboring amide groups exhibits enhanced biodegradability, and thus, has been studied as one of candidates for eco-friendly structural materials. However, the biodegradation mechanism for PA4 is far clear for a moment. We here examined the aggregation states of PA4 thin films coated on a hydrophobized SiOx substrate using atomic force microscopy (AFM) and neutron reflectivity (NR) analyses in air and water environments. AFM observation revealed that the outermost surface of the PA4 film was featureless and flat at a nanometer level. Once the film was immersed into water, the thickness increased by approximately 1.1 times. NR made it clear that the PA4 film was swollen due to the water sorption in the film, and that there existed multiple layers having different densities along the direction normal to the interface. Effect of annealing temperature on such the aggregation states and the degradability will be also discussed.
양한철,나경수,산전양성,성하진,정종철 한국농화학회 1989 Applied Biological Chemistry (Appl Biol Chem) Vol.32 No.4
Water-soluble crude polysaccharide (CAP-0) obtained from the Capsici Fructus(the fruits of Capsium annuum L.) showed a potent anti-complementary activity. The anti-complementary activity did not change by pronase digestion of CAP-0, but decreased by the periodate oxidation. CAP-0 was fractionated into four polysaccharide fractions, CAP-1, 2, 3 and 4, by the addition of cetyltrimethylammonium bromide. CAP-1, showing the highest anti-complementary activity, was refractioned by anion-exchange chromatography to give three major fractions(CAP-1-III, IV and V). CAP-1-III was shown to have low anti-complementary activity, but CAP-1-IV and V had high activity. CAP-1-III and IV were purified on Sephadex G-100 to give each two fractions(CAP-1-IIIa and IIIb, CAP-1-IVa and IVb), respectively. From the results of gel filtration and electrophoresis, these four fractions and CAP-1-V were found to be homogeneous polysaccharides. High molecular polysaccharies(M.W. CAP-1-IIIa 70,000, IVa 195,000, V 140,000) showed relatively higher anti-complementary activity than low molecular polysaccharides(CAP-1-IIIb and IVb).