67315-76-8Relevant articles and documents
Engineering the promiscuous racemase activity of an arylmalonate decarboxylase
Kourist, Robert,Miyauchi, Yusuke,Uemura, Daisuke,Miyamoto, Kenji
experimental part, p. 557 - 563 (2011/03/21)
Variant G74C of arylmalonate decarboxylase (AMDase) from Bordatella bronchoseptica has a unique racemising activity towards profens. By protein engineering, variant G74C/V43A with a 20-fold shift towards promiscuous racemisation was obtained, based on a reduced activity in the decarboxylation reaction and a two-fold increase in the racemisation activity. The mutant showed an extended substrate range, with a 30-fold increase in the reaction rate towards ketoprofen. Molecular dynamics simulations and the substrate profile of the racemase indicate that the steric and polar effects of the substrate structure play a more dominant role on catalysis than mere kinetic α-proton acidity. The observation that the conversion of β,γ-unsaturated carboxylic acids does not lead to a rearrangement to form their α,β isomers indicates a concerted rather than a stepwise mechanism. Interestingly, a substrate bearing a nitro group instead of the carboxylic acid group on the α-carbon atom was also converted by the racemase.
Kinetics and mechanism of hexachloroplatinate(IV) reduction by some neutralized α-hydroxy acids in a carbonate-hydrogencarbonate buffer medium
Pal, Biswajit,Sen Gupta, Kalyan Kali
, p. 553 - 560 (2007/10/03)
The kinetics of hexachloroplatinate(IV) reduction by some neutralized α-hydroxy acids such as glycolic, lactic, α-hydroxyisobutyric, mandelic, atrolactic, and benzilic acids in a carbonate-hydrogencarbonate buffer medium have been investigated. Platinum(IV) is reduced by the substrates to platinum(II) in a one-step two-electron process, whereas the substrates are oxidized to give formaldehyde, acetaldehyde, acetone, benzaldehyde, acetophenone, and benzophenone for the respective reactions. The pseudo- first-order rate constant is independent of the initial [platinum(IV)] as well as [OH-]. The reaction rate increases with increasing [substrate], but decreases with increasing chloride concentration. The reactions obey the following rate expression: -d[Pt(IV)](t)dr=kK(e)[A-][Pt(IV)]t/Cl-]+K(e)A- ]. The reactions proceed through an initial 1: 1 complex formation between the reactants, followed by decomposition of the complex to give the respective reaction products via C-C bond cleavage. The reactivity of the α- hydroxycarboxylate towards Pt(IV) are as follows: atrolactic acid > mandelic acid > benzilic acid > α-hydroxyisobutyric acid > lactic acid > glycolic acid. Thermodynamic parameters for the decomposition step have been evaluated. The mechanism of the reactions is discussed.
Reduction of manganate(VI) by mandelic acid and its significance to development of a general mechanism for oxidation of organic compounds by high-valent transition metal oxides
Lee, Donald G.,Chen, Tao
, p. 11231 - 11236 (2007/10/02)
Results obtained from a study of the oxidation of mandelic acid and cyclobutanol by manganate(VI) indicate that reaction mechanisms traditionally applied to oxidations of this type (i.e., hydrogen atom or hydride ion transfers) may not be correct. Instead it appears that the reaction may be initiated by a 2 + 2 addition of the α-C-H bond to a manganese oxo double bond. This interpretation may be useful in the development of a general mechanism for the oxidation of organic compounds by high-valent transition metal oxides including more common oxidants such as permanganate, ruthenium tetroxide, and chromic acid.
