Emissive Synthetic Cofactors: Enzymatic Interconversions of tzA Analogues of ATP NAD+ NADH NADP+ and NADPH

摘要

A series of enzymatic transformations, which generate visibly emissive isofunctional cofactors based on an isothiazolo[4,3-d]pyrimidine analogue of adenosine (>^tzA), was developed. Nicotinamide adenylyl transferase condenses nicotinamide mononucleotide and >^tzATP to yield >N^tzAD⁺, which can be enzymatically phosphorylated by NAD⁺ kinase and ATP or >^tzATP to the corresponding >N^tzADP⁺. The latter can be engaged in NADP-specific coupled enzymatic transformations involving conversion to >N^tzADPH by glucose-6-phosphate dehydrogenase and reoxidation to >N^tzADP⁺ by glutathione reductase. The >N^tzADP⁺/>N^tzADPH cycle can be monitored in real time by fluorescence spectroscopy.