Hung Mo Chen

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Asn182 --> Ala Aspergillus awamori glucoamylase expressed in Saccharomyces cerevisiae had a first-order thermodeactivation coefficient 40% that of wild-type glucoamylase at pH 4.5 between 60 degrees and 65 degrees C, caused by the elimination of an Asn-Gly sequence subject to deamidation and eventual chain breakage. Above 70 degrees C, and at pHs 3.5 and(More)
Exon amplification has been applied to a 2.5 Mb region of chromosome 21 that has been associated with some features of Down syndrome (DS). Identification of the majority of genes from this region will facilitate the correlation of the over-expression of particular genes with specific phenotypes of DS. Over 100 gene fragments have been isolated from this 2.5(More)
Both native Aspergillus niger glucoamylase and wild-type Aspergillus awamori glucoamylase expressed in Saccharomyces cerevisiae, which have identical primary structures, undergo hydrolysis at aspartyl bonds at low pH values and elevated temperatures. In native A.niger enzyme the Asp126-Gly127 bond was preferentially cleaved at pH 3.5, while at pH 4.5(More)
Aspergillus awamori glucoamylase is a secreted glycoprotein containing N-linked carbohydrate recognition sites at Asn-171, Asn-182 and Asn-395. Site-directed mutagenesis was performed at Asn-182 and Asn-395 to determine whether these residues were N-glycosylated by Saccharomyces cerevisiae, to investigate the function of any glycans linked to them, and to(More)
The feasibility of sequence analysis of the ribosomal 16S-23S intergenic spacer region (ITS) was evaluated for identification of 24 species of Streptococcus, one species of Abiotrophia, 18 species of Enterococcus and three species of Granulicatella. As GenBank currently lacks ITS sequence entries for many species of these four genera, the ITS sequences of(More)
Some species of enterococci and streptococci are difficult to differentiate by phenotypic traits. The feasibility of using an oligonucleotide array for identification of 11 viridans group streptococci was previously established. The aim of this study was to expand the array to identify species of Abiotrophia (1 species), Enterococcus (18 species),(More)
To decrease irreversible thermoinactivation of Aspergillus awamori glucoamylase, five Gly residues causing helix flexibility were replaced with Ala residues. Mutation of Gly57 did not affect thermostability. Mutation of Gly137 doubled it at pHs 3.5 and 4.5 but barely changed it at pH 5.5. The Gly139-->Ala mutation did not change thermostability at pH 3.5,(More)
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