Haiquan Yang

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In this study, the thermostability of an alkaline α-amylase from Alkalimonas amylolytica was significantly improved through structure-based rational and the introduction of multiple arginines (Arg) on the protein surface. Based on an analysis of the tertiary structure, seven residues (glutamine (Gln) 166, Gln 169, serine (Ser) 270, lysine (Lys) 315, Gln(More)
This work aims to improve the protein stability and catalytic efficiency of α-amylase from Bacillus subtilis under acidic conditions by site-directed mutagenesis. Based on the analysis of a three dimensional structure model, four basic histidine (His) residues His(222), His(275), His(293), and His(310) in the catalytic domain were selected as the mutation(More)
Gram-positive bacteria are widely used to produce recombinant proteins, amino acids, organic acids, higher alcohols, and polymers. Many proteins have been expressed in Gram-positive hosts such as Corynebacterium, Brevibacterium, and Streptomyces. The favorable and advantageous characteristics (e.g., high secretion capacity and efficient production of(More)
In this study, we constructed and expressed six fusion proteins composed of oligopeptides attached to the N terminus of the alkaline α-amylase (AmyK) from Alkalimonas amylolytica. The oligopeptides had various effects on the functional and structural characteristics of AmyK. AmyK-p1, the fusion protein containing peptide 1 (AEAEAKAKAEAEAKAK), exhibited(More)
High oxidative stability and catalytic efficiency are required for the alkaline α-amylases to keep the enzymatic performance under the harsh conditions in detergent industries. In this work, we attempted to significantly improve both the oxidative stability and catalytic efficiency of an alkaline α-amylase from Alkalimonas amylolytica by engineering the(More)
This work aims to improve the oxidative stability of alkaline amylase from Alkalimonas amylolytica through structure-based site-directed mutagenesis. Based on an analysis of the tertiary structure, five methionines (Met 145, Met 214, Met 229, Met 247, and Met 317) were selected as the mutation sites and individually replaced with leucine. In the presence of(More)
Many enzymes are efficiently produced by microbes. However, the use of natural enzymes as biocatalysts has limitations such as low catalytic efficiency, low activity, and low stability, especially under industrial conditions. Many protein engineering technologies have been developed to modify natural enzymes and eliminate these limitations. Commonly used(More)
An alkaline α-amylase gene from alkaliphilic Alkalimonas amylolytica was synthesized based on the preferred codon usage of Escherichia coli and Pichia pastoris, respectively, and then was expressed in the according heterologous host, E. coli BL21 (DE3) and P. pastoris GS115. The alkaline α-amylase expressed in E. coli was designated AmyA, whereas that(More)
Fusion constructs are used to improve the properties of or impart novel functionality to proteins for biotechnological applications. The biochemical characteristics of enzymes or functional proteins optimized by fusion include catalytic efficiency, stability, activity, expression, secretion, and solubility. In this review, we summarize the parameters of(More)
Background: Alkaline a-amylases have potential applications for hydrolyzing starch under high pH conditions in the starch and textile industries and as ingredients in detergents for automatic dishwashers and laundries. While the alkaline a-amylase gains increased industrial interest, the yield of alkaline a-amylases from wild-type microbes is low, and the(More)