Hypervalent Iodine(III)-Mediated Oxidative Decarboxylation of β-Keto Acids

2017 ◽  
Vol 6 (3) ◽  
pp. 262-264 ◽  
Author(s):  
Zhipeng Yuan ◽  
Tiantian Zhao ◽  
Tianyang Yu ◽  
Junru Wang ◽  
Hao Wei
2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 437-438
Author(s):  
Carolina Robles ◽  
Laura Gonzáles Davalos ◽  
Ofelia Mora ◽  
Yesmin Hermanadez ◽  
Armando Shimada ◽  
...  

Abstract Alpha lipoic acid (LA) is a potent nutritional antioxidant. It is a derivate of octanoic acid containing a cyclic disulfide bond. An LA complex with lysine-lipoamide, functions as a co-factor in the mitochondrial dehydrogenase that catalyzes the oxidative decarboxylation of α-keto acids. In this reaction, LA is reduced to dihydrolipoic acid (DHLA), which interacts with reactive oxygen species, and LA can also inactivate free radicals. Another important role of DHLA is in signal transduction by activating insulin receptors, which causes glucose transporters translocation from cytoplasm to the cell surface. Due to its potential antioxidant effect at ruminal level, the aim of this study was to evaluate the effect of fed LA on productive parameters, ruminal fatty volatile fatty acid (VFA) concentration and blood glucose of sheep. Sixty-four, two-months-old, crossbred lambs were penned in groups of four, divided into four treatments: 0, 40, 80, and 120 ppm LA in diet. During 84 days, every 28 days on two consecutive days, animals were weighed (to determine average daily weight gain, DWG), blood and ruminal fluid were taken for glucose and VFA quantification, respectively. All variables were analyzed in a completely randomized design. DWG was statistically higher in those animals receiving 80 ppm (250 g) as compared to the rest (200, 188, 180 g for 120, 40, 0 ppm, respectively) (P < 0.0001). No differences in blood glucose or ruminal VFA were found (P > 0.1). LA could improve the productive performance of sheep; however, it would be necessary to study the role of LA and its effects on the ruminal microbiome and its action mechanism. Research support by Project PAPIIT-UNAM IN211518


1958 ◽  
Vol 29 (1) ◽  
pp. 218-219 ◽  
Author(s):  
D.R. Sanadi ◽  
Martha Langley ◽  
Fred White

1990 ◽  
Vol 31 (2) ◽  
pp. 201-204 ◽  
Author(s):  
R.M. Moriarty ◽  
R.K. Vaid ◽  
T.E. Hopkins ◽  
B.K. Vaid ◽  
O. Prakash†

2020 ◽  
Vol 295 (32) ◽  
pp. 11246-11261 ◽  
Author(s):  
Duangthip Trisrivirat ◽  
Narin Lawan ◽  
Pirom Chenprakhon ◽  
Daisuke Matsui ◽  
Yasuhisa Asano ◽  
...  

l-Lysine oxidase/monooxygenase (l-LOX/MOG) from Pseudomonas sp. AIU 813 catalyzes the mixed bioconversion of l-amino acids, particularly l-lysine, yielding an amide and carbon dioxide by an oxidative decarboxylation (i.e. apparent monooxygenation), as well as oxidative deamination (hydrolysis of oxidized product), resulting in α-keto acid, hydrogen peroxide (H2O2), and ammonia. Here, using high-resolution MS and monitoring transient reaction kinetics with stopped-flow spectrophotometry, we identified the products from the reactions of l-lysine and l-ornithine, indicating that besides decarboxylating imino acids (i.e. 5-aminopentanamide from l-lysine), l-LOX/MOG also decarboxylates keto acids (5-aminopentanoic acid from l-lysine and 4-aminobutanoic acid from l-ornithine). The reaction of reduced enzyme and oxygen generated an imino acid and H2O2, with no detectable C4a-hydroperoxyflavin. Single-turnover reactions in which l-LOX/MOG was first reduced by l-lysine to form imino acid before mixing with various compounds revealed that under anaerobic conditions, only hydrolysis products are present. Similar results were obtained upon H2O2 addition after enzyme denaturation. H2O2 addition to active l-LOX/MOG resulted in formation of more 5-aminopentanoic acid, but not 5-aminopentamide, suggesting that H2O2 generated from l-LOX/MOG in situ can result in decarboxylation of the imino acid, yielding an amide product, and extra H2O2 resulted in decarboxylation only of keto acids. Molecular dynamics simulations and detection of charge transfer species suggested that interactions between the substrate and its binding site on l-LOX/MOG are important for imino acid decarboxylation. Structural analysis indicated that the flavoenzyme oxidases catalyzing decarboxylation of an imino acid all share a common plug loop configuration that may facilitate this decarboxylation.


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