Physical Representation Learning and Parameter Identification from Video Using Differentiable Physics

International Journal of Computer Vision - Representation learning for video is increasingly gaining attention in the field of computer vision. For instance, video prediction models enable activity...     

Stereo‐Controlled Asymmetric Bioreduction of α,β‐Dehydroamino Acid Derivatives

α,β‐Dehydroamino acid derivatives proved to be a novel substrate class for ene‐reductases from the ‘old yellow enzyme’ (OYE) family. Whereas N‐acylamino substituents were tolerated in the α‐position, β‐analogues were generally unreactive. For aspartic acid derivatives, the stereochemical outcome of the bioreduction using OYE3 could be controlled by variation of the N‐acyl protective group to furnish the corresponding (S)‐ or (R)‐amino acid derivatives. This switch of stereopreference was explained by a change in the substrate binding, by exchange of the activating ester group, which was proven by ²H‐labelling experiments.     

Asymmetric Bioreduction of CC Bonds using Enoate Reductases OPR1, OPR3 and YqjM: Enzyme‐Based Stereocontrol

Three cloned enoate reductases from the “old yellow enzyme” family of flavoproteins were investigated in the asymmetric bioreduction of activated alkenes. 12‐Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from Lycopersicon esculentum (tomato), and YqjM from Bacillus subtilis displayed a remarkably broad substrate spectrum by reducing α,β‐unsaturated aldehydes, ketones, maleimides and nitroalkenes. The reaction proceeded with absolute chemoselectivity – only the conjugated CC bond was reduced, while isolated olefins and carbonyl groups remained intact – with excellent stereoselectivities (ees up to >99%). Upon reduction of a nitroalkene, the stereochemical outcome could be determined via choice of the appropriate enzyme (OPR1 versus OPR3 or YqjM), which furnished the corresponding enantiomeric nitroalkanes in excellent ee. Molecular modelling suggests that this “enzyme‐based stereocontrol” is caused by subtle differences within the active site geometries.