Nonribosomal peptide synthetases (NRPSs) are multifunctional enzymes consisting of catalytic domains. The substrate specificities of adenylation (A) domains determine the amino-acid building blocks to be incorporated during nonribosomal peptide biosynthesis. The A-domains mediate ATP-dependent activation of amino-acid substrates as aminoacyl-O-AMP with pyrophosphate (PPi) release. Traditionally, the enzymatic activity of the A-domains has been measured by radioactive ATP-[(32)P]-PPi exchange assays with the detection of (32)P-labeled ATP. Recently, we developed a colorimetric assay for the direct detection of PPi as a yellow 18-molybdopyrophosphate anion ([(P2O7)Mo18O54](4-)). [(P2O7)Mo18O54](4-) was further reduced by ascorbic acid to give a more readily distinguishable blue coloration. Here we demonstrate the lab protocols for the colorimetric assay of PPi released in A-domain reactions.
CITATION STYLE
Maruyama, C., Niikura, H., Takakuwa, M., Katano, H., & Hamano, Y. (2016). Colorimetric Detection of the Adenylation Activity in Nonribosomal Peptide Synthetases (pp. 77–84). https://doi.org/10.1007/978-1-4939-3375-4_5
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