Enzyme-based systems and methods for synthesizing the NAD precursors NMN and NaMN are disclosed. Such methods and systems utilize a mutated form of phosphoribosylpyrophosphate synthetase (PRS) that is superactive and/or other enzyme or enzyme combinations that are immobilized onto a solid surface. The methods and systems substantially increase the efficiency and yield of NAD precursor synthesis.

This disclosure provides mutant genes related to drug resistance and relapse of acute lymphoblastic leukaemia (ALL) and a use thereof, treatment or prevention of drug resistance and relapse of ALL and a use thereof, a use of compound Lometrexol and related inhibitors targeting GART and AITC in prevention and treatment of drug resistance and relapse of ALL, and a kit for evaluation of the risk of drug resistance and relapse of ALL. The mutation gene is a mutant gene of PRPS1. The drug acts on enzymes in purine synthesis pathway and reduces drug resistance and relapse by decreasing the concentration of hypoxanthine. The kit comprises reagents for lysis of sample cells and an instruction, wherein the instruction comprises: (i) collection and lysis of the sample cells; (b) determination of the contents of hypoxanthine, IMP, AICAR and Inosine; (c) evaluation of the risk of the drug resistance and relapse of ALL. The invention provides a powerful technical means and support for the prevention and treatment of drug resistance and relapse of ALL.

Enzyme-based systems and methods for synthesizing the NAD precursors NMN and NaMN are disclosed. Such methods and systems utilize a mutated form of phosphoribosylpyrophosphate synthetase (PRS) that is superactive and/or other enzyme or enzyme combinations that are immobilized onto a solid surface. The methods and systems substantially increase the efficiency and yield of NAD precursor synthesis.

The present invention provides a method for preparing nicotinamide mononucleotide (NMN) by biocatalysis. The method includes a step of catalytically reacting a plurality of raw materials including nicotinamide, ATP, and ribose in the presence of nicotinamide phosphoribosyltransferase (Nampt), ribose phosphate pyrophosphokinase, and ribokinase, to prepare the NMN.