A high yield of l-homoalanine can be obtained by an engineered dual cofactor-dependent GluDH in a cascade without the addition of NAD(P)H.

No abstract

Background: Carboxylic acid reductases (CARs) represent useful tools for the production of aldehydes from ubiquitous organic carboxylic acids. However, the low catalytic efficiency of these enzymes hampers their application.Methods: Herein, a CAR originating from Mycobacterium smegmatis was redesigned through rational hinge engineering to enhance the catalytic efficiency.Results: Based on the unique domain architecture of CARs and their superfamily, a mutagenesis library of the hinge region was designed. The best mutant R505I/N506K showed a 6.57-fold improved catalytic efficiency. Molecular dynamics simulations showed the increased catalytic efficiency was due to the strong binding of the acyl-AMP complex with it. Meanwhile, the ε-nitrogen atom of Lys610 frequently interacted with the ribose-ring oxygen atom of the complex, the distance (d1) between them represents a great indicator for that. The d1 value was used as a nimble indicator to evaluate unexplored mutants of that region for enhanced activity by in silico mutational experiments. Overall, eight mutants were identified to show higher enhanced activity compared with wild-type enzyme and R505F/N506G showed the highest catalytic efficiency.Conclusion: Altogether, the two-step strategy used here provided useful references for the engineering of CARs and other similar multiple-domain enzymes.

Typhoon Haikui (2012) occurred in the northwestern Pacific Ocean, and landfall on the east coast of China brought heavy rainfall with strong winds. Because of Typhoon Haikui, sea surface temperature (SST) cooling of 3 °C occurred on the right side of the track, mainly due to Ekman transport and upwelling. SST cooling on the left side was lower than on the right side, mainly due to the rainfall. Heavy precipitation occurred on both sides of the typhoon track; however, rainfall was higher on the left side of the typhoon track. This paper explains the dynamic process between atmospheric and oceanographic parameters and verifies the variations in chlorophyll and sea surface height data before, during, and after the typhoon. Typhoon Haikui demonstrates dynamic variations and intuitively illustrates the relationship between the ocean and atmospheric parameters.

No abstract