The Nitrogen Atom of Vitamin B6 Is Essential for the Catalysis of Radical Aminomutases.

Radical aminomutases are pyridoxal 5'-phosphate (PLP, a B6 vitamer)-dependent enzymes that require the generation of a 5'-deoxyadenosyl radical to initiate the catalytic cycle, to perform a 1,2 amino group shift reaction. The role of the nitrogen atom of PLP in radical aminomutases has not been investigated extensively yet. We report an alternative synthetic procedure to provide easy access to 1-deazaPLP (dAPLP), an isosteric analog of PLP which acts as a probe for studying the role of the nitrogen atom. Our results revealed that lysine 5,6-aminomutase (5,6-LAM), a radical aminomutase, reconstituted with dAPLP cannot turn over a substrate, demonstrating that the nitrogen atom is essential for radical aminomutases. In contrast, biochemical and spectroscopic studies on the S238A variant reconstituted with PLP revealed a minuscule loss of activity. This apparent anomaly can be explained by a water-mediated rescue of activity in S238A, as if mimicking the active site of lysine 2,3-aminomutase. This study leads to a better comprehension of how enzymes harness the optimum capability of PLP to realize catalysis.

Primulinasilaniae sp. nov. (Gesneriaceae) from the limestone area of Guizhou Province, China.

Primulinasilaniae X.X.Bai & F.Wen, a new species of Primulina Hance (Gesneriaceae) from the limestone area of Wangmo County, Guizhou Province, is described and illustrated. The new species is similar to P.spiradiclioides Z.B.Xin & F.Wen, but can be easily distinguished from the latter by a combination of characteristics, especially in the lateral veins of its leaf and floral shape and tube. At present, three populations in one locality of this new taxon were found, totaling about 600 mature individuals. According to the IUCN Red List Categories and Criteria (Version 3.1), the species is provisionally assessed as Vulnerable [VU D1].

Liver cold preservation induce lung surfactant changes and acute lung injury in rat liver transplantation.

AIM: To investigate the relationship between donor liver cold preservation, lung surfactant (LS) changes and acute lung injury (ALI) after liver transplantation. METHODS: Liver transplantation models were established using male Wistar rats. Donor livers were preserved in University of Wisconsin solution at 4  °C for different lengths of time. The effect of ammonium pyrrolidinedithiocarbamate (PDTC) on ALI was also detected. All samples were harvested after 3 h reperfusion. The severity of ALI was evaluated by lung weight/body weight ratio, lung histopathological score, serum nitric oxide (NO) and endothelin (ET)-1 levels, lung tumor necrosis factor (TNF)-α and interleukin (IL)-1ß levels. Lung surfactants (LSs) were determined by micellar electrokinetic capillary chromatography. RESULTS: With extended donor liver cold preservation time (CPT), lung histopathological scores, serum ET-1 levels, lung weight/body weight ratio and the level of TNF-α and IL-1ß in lung were increased significantly in the 180-min group compared with the sham group (3.16 ± 0.28 vs 1.12 ± 0.21, P < 0.001; 343.59 ± 53.97 vs 141.53 ± 48.48, P < 0.001; 0.00687 ± 0.00037 vs 0.00557 ± 0.00056, P < 0.001; 17.5 ± 3.0 vs 1.3 ± 0.3, P < 0.001; 10.8 ± 2.3 vs 1.8 ± 0.4, P < 0.001), but serum NO levels decreased remarkably (74.67 ± 10.01 vs 24.97 ± 3.18, P < 0.001). The expression of lung phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) increased when CPT was < 120 min, and decreased when CPT was > 180 min (PC: 1318.89 ± 54.79 vs 1011.18 ± 59.99, P < 0.001; PE: 1504.45 ± 119.96 vs 1340.80 ± 76.39, P = 0.0019; PI: 201.23 ± 34.82 vs 185.88 ± 17.04, P = 0.2265; PS: 300.43 ± 32.95 vs 286.55 ± 55.55, P = 0.5054). All these ALI-associated indexes could be partially reversed by PDTC treatment. CONCLUSION: Prolonged CPT could induce or inhibit the expression of LSs at the compensation or decompensation stage, and some antioxidants (e.g., PDTC) may reverse the pathological process partially.