123175-89-3Relevant academic research and scientific papers
Stereochemical aspects of the bioreduction of the conjugated double bond of perillaldehyde
Fronza, Giovanni,Fuganti, Claudio,Pinciroli, Matteo,Serra, Stefano
, p. 3073 - 3077 (2004)
A study on the regioselective reduction of the conjugate double bond of perillaldehyde is described. The chemical reduction of this substrate was investigated in order to provide a straightforward access to the relevant natural flavour, dihydroperillaldehyde. The biological reduction of both natural (S)-(-)-perillaldehyde and synthetic (R)-(+)-perillaldehyde was accomplished by means of fermenting baker's yeast. The latter microorganism converted, with different diastereoselectivity, the (S)- and (R)-enantiomers into the corresponding trans and cis saturated alcohols, respectively. The origin of the hydrogen atoms added to the double bond was studied by deuterium labelling experiments and 2H NMR measurements that clearly demonstrate a different mechanism of the biohydrogenation of the two enantiomeric forms of perillaldehyde.
Loop-Grafted Old Yellow Enzymes in the Bienzymatic Cascade Reduction of Allylic Alcohols
Reich, Sabrina,Nestl, Bettina M.,Hauer, Bernhard
, p. 561 - 565 (2016/04/26)
The enzymatic reduction of C=C bonds in allylic alcohols with Old Yellow Enzymes represents a challenging task, due to insufficient activation through the hydroxy group. In our work, we coupled an alcohol dehydrogenase with three wild-type ene reductases - namely nicotinamide-dependent cyclohex-2-en-1-one reductase (NCR) from Zymomonas mobilis, OYE1 from Saccharomyces pastorianus and morphinone reductase (MR) from Pseudomonas putida M10 - and four rationally designed β/α loop variants of NCR in the bienzymatic cascade hydrogenation of allylic alcohols. Remarkably, the wild type of NCR was not able to catalyse the cascade reaction whereas MR and OYE1 demonstrated high to excellent activities. Through the rational loop grafting of two intrinsic β/α surface loop regions near the entrance of the active site of NCR with the corresponding loops from OYE1 or MR we successfully transferred the cascade reduction activity from one family member to another. Further we observed that loop grafting revealed certain influences on the interaction with the nicotinamide cofactor.
Site-saturation mutagenesis of tryptophan 116 of saccharomyces pastorianus old yellow enzyme uncovers stereocomplementary variants
Padhi, Santosh Kumar,Bougioukou, Despina J.,Stewart, Jon D.
experimental part, p. 3271 - 3280 (2009/07/30)
Site-saturation mutagenesis was used to generate all possible replacements for Trp 116 of Saccharomyces pastorianus (formerly Saccharomyces carlsbergensis) old yellow enzyme (OYE). Our original hypothesissthat smaller amino acids at position 116 would allow better acceptance of bulky 3-alkylsubstituted 2-cyclohexenonessproved incorrect. Instead, Phe and Ile replacements favored the binding of some substrates in an opposite orientation, which yielded reversed stereochemical outcomes compared to that of the wild-type OYE. For example, W116I OYE reduced (R)- and (S)-carvone to enantiomeric products, rather than the diastereomers produced by the wild-type OYE. Deuterium labeling revealed that (S)-carvone reduction by the W116I OYE occurred by the same pathway as that by the wild type (net trans-addition of H2), proving that different substrate binding orientations were responsible for the divergent products. Trp 116 mutants also afforded different stereochemical outcomes for reductions of (R)- perillaldehyde and neral. Preliminary studies of an OYE family member whosenative sequence contains Ile at position 116 (Pichia stipitis OYE 2.6) revealed that this enzyme's stereoselectivity matched that of the wild-t ype S. pastorianus OYE, showing that the identity of the residue at position 116 does not solely determine the substrate binding orientation. Computational docking studies using an induced fit methodology successfully reproduced the majority of the experimental outcomes. These computational tools will allow preliminary in silico screening of additional residues to identify those most likely to control the substrate binding orientation and provide some guidance to future experimental studies.
