Extracellular Hydrolysis of NAD+and its Secondary Metabolites by a new Aspergillus sp

Abstract

In some organisms, the metabolism of extracellular nicotinamide adenine dinucleotide (NAD+) plays an important role in purine salvage and uptake. Since filamentous fungi are used to degrade NAD and produce beneficial secondary metabolites, various enzymes, fermented foods and organic acids. Many strains belonging to filamentous fungi were screened for the enzymes production that catalyzed hydrolytic dephosphorylation and deamination of NAD and its secondary metabolites. A fungal isolate which was found to be the most prominent strain was identified genetically as Aspergillus fumigatous. Extracts of this new strain catalyzes the hydrolysis the ester bond between the two nucleotides of NAD by pyrophosphatase activity, which catalyzes NAD to nicotinamide mononucleotide (NMN) and adenosine monophosphate (AMP), at that point NMN and AMP are hydrolyzed to nicotinamide riboside (NR) and adenosine separately by 5’–nucleotidase activity This research reports also existence of deaminase activity hydrolyzed adenosine to inosine. The study demonstrated major enzymatic pathways involved in NAD degradation and identification of intermediates formed by Aspergillus fumigatous. Separation and partial purification of these enzymes and some kinetic properties of them were achieved