PlumX Metrics
Embed PlumX Metrics

Evidence for only oxygenative cleavage of aldehydes to alk(a/e)nes and formate by cyanobacterial aldehyde decarbonylases

Biochemistry, ISSN: 1520-4995, Vol: 51, Issue: 40, Page: 7908-7916
2012
  • 122
    Citations
  • 0
    Usage
  • 119
    Captures
  • 0
    Mentions
  • 0
    Social Media
Metric Options:   Counts1 Year3 Year

Metrics Details

Article Description

Cyanobacterial aldehyde decarbonylases (ADs) catalyze the conversion of C fatty aldehydes to formate (HCO) and the corresponding C alk(a/e)nes. Previous studies of the Nostoc punctiforme (Np) AD produced in Escherichia coli (Ec) showed that this apparently hydrolytic reaction is actually a cryptically redox oxygenation process, in which one O-atom is incorporated from O into formate and a protein-based reducing system (NADPH, ferredoxin, and ferredoxin reductase; N/F/FR) provides all four electrons needed for the complete reduction of O . Two subsequent publications by Marsh and co-workers [Das, et al. (2011) Angew. Chem. Int. Ed.50, 7148-7152; Eser, et al. (2011) Biochemistry50, 10743-10750] reported that their Ec-expressed Np and Prochlorococcus marinus (Pm) AD preparations transform aldehydes to the same products more rapidly by an O-independent, truly hydrolytic process, which they suggested proceeded by transient substrate reduction with obligatory participation by the reducing system (they used a chemical system, NADH and phenazine methosulfate; N/PMS). To resolve this discrepancy, we re-examined our preparations of both AD orthologues by a combination of (i) activity assays in the presence and absence of O and (ii) O and HO isotope-tracer experiments with direct mass-spectrometric detection of the HCO product. For multiple combinations of the AD orthologue (Np and Pm), reducing system (protein-based and chemical), and substrate (n-heptanal and n-octadecanal), our preparations strictly require O for activity and do not support detectable hydrolytic formate production, despite having catalytic activities similar to or greater than those reported by Marsh and co-workers. Our results, especially of the O-tracer experiments, suggest that the activity observed by Marsh and co-workers could have arisen from contaminating O in their assays. The definitive reaffirmation of the oxygenative nature of the reaction implies that the enzyme, initially designated as aldehyde decarbonylase when the C1-derived coproduct was thought to be carbon monoxide rather than formate, should be redesignated as aldehyde-deformylating oxygenase (ADO). © 2012 American Chemical Society.

Bibliographic Details

Ning Li; Wei-chen Chang; Douglas M. Warui; Squire J. Booker; Carsten Krebs; J. Martin Bollinger Jr.

American Chemical Society (ACS)

Biochemistry, Genetics and Molecular Biology

Provide Feedback

Have ideas for a new metric? Would you like to see something else here?Let us know