A novel recombinant chlorophyllase from cyanobacterium Cyanothece sp. ATCC 51142 for the production of bacteriochlorophyllide a

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Abstract
Bacteriopheophorbide a (BPheid a) is used as a precursor for bacteriochlorin a (BCA), which can be used for photodynamic therapy in both in vitro and in vivo biochemical applications. This study successfully isolated and expressed a photosynthetic bacterium (Cyanothece sp. ATCC 51142) chlorophyllase called CyanoCLH, which can be used as a biocatalyst for the production of a BCA precursor by degrading bacteriochlorophyll a (BChl a). Substrate specificity and enzyme kinetic analyses were performed and the results verified that the recombinant CyanoCLH preferred hydrolyzing BChl a to produce bacteriochlorophyllide a (BChlide a), which can be converted to BPheid a by removing magnesium ion. The recombinant CyanoCLH was cloned and expressed in Escherichia coli BL‐21 (DE3), and its molecular weight was 54.7 kDa. The deduced amino acid sequence of the recombinant CyanoCLH comprised a unique lipase‐motif GHSLG, which differs from the GHSRG sequence of other plants and lacks a histidine of the typical and conserved catalytic triad Ser‐Asp‐His. The recombinant CyanoCLH was subjected to biochemical analyses, and the results indicated that its optimal pH and temperature were 7.0 and 60 °C, respectively.
Funding Information
  • Ministry of Education, Taiwan
  • National Science Council (NSC 101-2313-B-214-002-MY3)

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