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KMID : 1094720100150010131
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Biotechnology and Bioprocess Engineering
2010 Volume.15 No. 1 p.131 ~ p.138
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A Novel NAD+-dependent Aldehyde Dehydrogenase Encoded by the puuC Gene of Klebsiella pneumoniae DSM 2026 that Utilizes 3-Hydroxypropionaldehyde as a Substrate
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Subramanian Mohan Raj
Chelladurai Rathnasingh
Jung Woo-Chel
Edwardraja Selvakumar
Park Sung-Hoon
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Abstract
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3-Hydroxypropionic acid (3-HP), a versatile and valuable platform chemical, has diverse industrial applications; but its biological production from glycerol is often limited by the capability of the enzyme aldehyde dehydrogenase (ALDH) to convert an intermediary compound, 3-hydroxypropionaldehyde (3-HPA), to 3-HP. In this study, we report a new ALDH, PuuC, from Klebsiella pneumoniae DSM 2026, that efficiently converts 3-HPA to 3-HP. The identified gene puuC was cloned, expressed in Escherichia coli, purified, and characterized for its properties. The recombinant enzyme with a molecular weight of 53.8 kDa exhibited broad substrate specificity for various aliphatic aldehydes, especially C2-C5 aldehydes. NAD+ was the preferred coenzyme for the oxidation of most aliphatic and aromatic aldehydes tested. The optimum pH and temperature for PuuC activity were pH 8.0 and 45oC. The Km values for 3-HPA and NAD+ were 0.48 and 0.09 mM, respectively. The activity of PuuC was enhanced in the presence of reducing agents such as 2-mercaptoethanol or dithiothreitol, while several metal ions, particularly Hg2+, Ag+, and Cu2+ inhibited its activity. The predicted structure of PuuC indicated the presence of K191 and E194 in close proximity to the glycine motif, suggesting that PuuC belongs to class 2 ALDHs.
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KEYWORD
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3-hydroxypropionaldehyde dehydrogenase, 3-hydroxypropionic acid, aldehyde dehydrogenase, PuuC, ALDH, Klebsiella pneumoniae
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