A novel strain of Levilactobacillus brevis PDD-5 isolated from salty vegetables has beneficial effects on hyperuricemia through anti-inflammation and improvement of kidney damage

Hyperuricemia is a metabolic disorder caused by abnormal purine metabolism,resulting in abnormally high serum uric acid.In this study,a novel Levilactobacillus brevis PDD-5 isolated from salty vegetables was verified with the function of alleviating hyperuricemia.The relevant effects of L.brevis PDD-5 in lowering uric acid were analyzed by in vitro and in vivo experiments.The results showed that the L.brevis PDD-5 has(68.86±15.46)%of inosine uptake capacity and(95.75±3.30)%of guanosine uptake capacity in vitro.Oral administration of L.brevis PDD-5 to hyperuricemia rats reduced uric acid,creatinine,and urea nitrogen in serum,as well as decreased inosine and guanosine levels in the intestinal contents of rats.Analysis of relevant markers in the kidney by ELISA kits revealed that L.brevis PDD-5 alleviated oxidative stress and inflammation.Moreover,the gene expression of uric acid transporter 1(URAT1)and glucose transporter 9(GLUT9)was down-regulated,and the gene expression of organic anion transporter 1(OAT1)was up-regulated after treatment with L.brevis PDD-5.Western blot analysis showed that L.brevis PDD-5 alleviated hyperuricemia-induced kidney injury through the NLRP3 pathway.The se findings suggest that L.brevis PDD-5 can lower uric acid,repair kidney damage,and also has the potential to prevent uric acid nephropathy.

Structural Insight into the Binding of Hypoxanthine with Purine Nucleoside Phosphorylase from Streptococcus mutants

Purine nucleoside phosphorylase is a key enzyme in the purine-salvage pathway and an attractive target for drug design. The crystal structure of Streptococcus mutants purine nucleoside phosphorylase（Smu PNP） has been solved by molecular replacement at 1.80 resolution and refined to R factors of 19.9%/23.7%（Rcryst/Rfree） . Sequence alignment and structural comparison show that Smu PNP has more similarity with PNPs isolated from human and malarial sources than the bacterial PNPs. The structure complexed with hypoxanthine（HPA） and sulfate ion was solved at 2.24A resolution and refined to R factors of 21.6%/24.1%（Rcryst/Rfree） . It is interesting to note that the resulting electron density indicated the product,HPA,presents in the active site although inosine was included in the crystallization mixture with Smu PNP. Asn233 and Glu191 are the important residues for ligand binding and recognition. Comparison with PNPs from different species gives detailed information about binding of small molecules on the active site,which is important for the studies of enzymatic mechanism and rational design of specific inhibitors for PNPs.

Two-step Enzymatic Synthesis of Guanine Arabinoside

The chemical synthesis of Guanine arabinoside （ara-G） is extremely complex, time-consuming, and seriously polluted. A two-step enzymatic synthesis process was developed to acquire ara-G easily. 2,6-Diaminopurine arabinoside （ara-DA） was first synthesized with purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase produced by Enterobacter aerogenes DGW-07. The conversion yield of ara-DA could reach above 90% when the reaction liquid contained 30 mmol·L^-1 uracil arabinoside as arabinose donor, 10 mmol·L^- 1 2,6-diaminopurine as arabinose acceptor in pH 7.0 20 mmol·L^-1 phosphate buffer, and reacted at 60℃ for 48h. Then, ara-DA was effectively transformed into ara-G with adenylate deaminase produced by Aspergillus oryzae DAW-01. The total process had no complex separation and purification.