D-Glucuronic acid lactone is an endogenous metabolite. In the presence of iron salts and hydrogen peroxide, D-glucuronic acid was converted into D-glucaric acid. Microsomal preparations in the presence of NADPH also produced D-glucarate from D-glucuronic acid, presumably due to formation of hydrogen peroxide, and the product was an inhibitor of beta-D-glucuronidase[1]. Amount of D-glucaric acid, L-ascorbic acid, and D-glucuronic acid in urine increased in the case of the alloxan diabetic rabbits. L-Gulonic acid dehydrogenase, lactonase II, and beta-glucuronidase activities were reduced, and UDPGA-pyrophosphatase, D-glucuronic acid-1-phosphatase, and UDPGA-transferase activities increased in the diabetic rabbit liver[2]. Agrobacterium tumefaciens uronate dehydrogenase (AtuUdh) belongs to the short-chain dehydrogenase superfamily, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. It is apparently required for the production of D-glucaric acid. AtuUdh-catalyzed reaction is reversible with dual substrate-specific activity (D-galacturonic acid and D-glucuronic acid) in nature. Q14F, S36L, and S75T mutants have shown a high binding affinity to D-glucuronic acid and its substrate intermediates such as D-glucaro-1,4-lactone and D-glucaro-1,5-lactone. D34S, N112E and S165E mutants found to show a high selectivity of D-galacturonic acid and its substrate intermediates for D-galactaric acid production[3].
搜索
