Kinetics of oxidation of amino acids by alkaline hexacyanoferrate(III)

Abstract

The kinetics of the oxidation of a-amino acids (glutamic acid and aspartic acid) by alkaline hexacyanoferrate(Il1) were studied at constant ionic strength and over the temperature range 323-348 K. The rate was dependent on the first power of the concentrations of substrate and oxidant, but was independent of the concentration of alkali in the range studied. The value of k~/ k~ was in the range 8.1-8.3 for the slow step, indicating the loss of a hydrogen atom from the C-H bond, giving a radical species which was characterized by ESR spectroscopy. The reaction proceeds by way of the a-imino acid, formed in a fast step, which undergoes hydrolysis to give the corresponding a-keto acid.

Kinetics of the Oxidation of L-Cysteine by trans- and cis-Cobalt(III) and Iron(III) Complexes

“…Sharma et al [7] reported the reactivity of iron(V) and iron(VI) with both glycine and α-alanine, at pH 12.4 and 23 -24 • C, using stopped-flow and pulse radiolysis techniques. Laloo et al [8] studied the kinetics of the oxidation of three amino acids (lysine, arginine, and histidine) by alkaline hexacyanoferrate(III) at constant ionic strength over the temperature range 318 -338 K. Jameson et al [9,10] reported anaerobic oxidation of cysteine to cystine by iron(III) in acidic solution using stopped-flow high-speed spectrophotometry. The oxidation of amino acids to aldehydes, in the presence of Os(VIII) as a catalyst, by alkaline hexacyanoferrate(III) has been reported by Mehrotra et al [11].…”

Oxidation of Free L-histidine by tert-Butylhydroperoxide

“…In general, the products from the oxidation of amino acids by Fenton chemistry are NH 4 + , carbon dioxide, oximes, α-ketoacids and upon the loss of a carbonyl, the corresponding aldehyde, which is further oxidized to a carboxylic acid (13,14). Known metal catalyzed oxidation products of L-histidine include aspartate, 2-oxohistidine, (15,16) imidazole pyruvic acid, (17,18), 4(5)-imidazole acetaldehyde (19)(20)(21)(22), 4(5)-imidazole acetic acid (23), imidazole lactic acid (23), 4(5)-imidazole acetonitrile (19,20,24,25), and β-imidazolylpyruvic acid (17,18).…”

Mechanistic Aspects of Os(VIII)/Ru(III) Catalysed Oxidation of L-phenylalanine by Ag(III) Periodate Complex in Aqueous Alkaline Medium

“…The oxidation of amino acids is of interest as the oxidation products differ for different oxidants [1,2]. Thus, the study of amino acids becomes important because of their biological significance and selectivity towards the oxidants.…”