14009-94-0Relevant articles and documents
Effect of Cholesterol on the Stereoselective Hydrolysis in Artificial Membrane Systems
Ueoka, Ryuichi,Matsumoto, Yoko
, p. 3774 - 3778 (1984)
The catalytic efficiency and enantioselectivity for the hydrolysis of p-nitrophenyl N-dodecanoyl-D(L)-phenylalaninate (2b) in the catalytic system of N-tetradecanoyl-L-histidyl-L-leucine (1b) and didodecyldimethylammonium bromide (3a) were enhanced by addition of cholesterol at an optimum temperature (25 deg C).Furthermore, it is suggested that the hydrophobic interaction between reactants in the bilayer membrane system (3a) might be reduced by adding cholesterol on the basis of isokinetic temperature.It is concluded from these results that the fluidity of the artificial bilayer matrix (3a) varies upon addition of cholesterol.
Targeting peptides with an iron-based oxidant: Cleavage of the amino acid backbone and oxidation of side chains
Ekkati, Anil R.,Kodanko, Jeremy J.
, p. 12390 - 12391 (2008/03/30)
The oxidation of protected amino acids using an iron-based oxidant is described. Substrates of the general formula Ac-X-NHtBu, where X = Gly (1), Ala (2), Val (3), Phe (4), Tyr (5), Trp (6), and Met (7) were constructed to model individual amino acid residues within a polypeptide chain. Oxidation of 1 by the iron catalyst [FeII(N4Py)(MeCN)](ClO4)2 (8) and KHSO5 leads to scission of the amino acid backbone and produces N-acetylformamide as the major product. Decomposition of the iron-based oxidant [FeIV(O)(N4Py)]2+, derived from 8, is slower in the presence of 2,2-d2-1 (96% D) than with 1, giving a kinetic isotope effect of 4.8, which is consistent with [FeIV(O)(N4Py)]2+ cleaving an α-CH bond of 1. Aliphatic amino acid substrates 2 and 3 do not react with [FeIV(O)(N4Py)]2+ under the same conditions used with 1. With substrates 4-7 oxidation of the amino acid side chain is observed. Decomposition of [FeIV(O)(N4Py)]2+ upon treatment with 10 equiv of 1 and 4-7 revealed that 5 is the most reactive toward the FeIVO species. Pseudo-first-order rate constants of 17.0(5) × 10-3, 3.15(8) × 10-3 and 5.8(2) × 10-5 s-1 were obtained for decomposition of [FeIV(O)(N4Py)]2+ ([Fe] = 1 mM, 1:1 H2O/MeCN) by 6, 7, and 1, respectively. Copyright