ROSA PASCUAL and MIGUEL A. HERRAEZ. Can. J. Chem. 63, 2349 (1985). The kinetics of oxidation of serine and threonine by periodate have been investigated in acid medium at 10°C. The reaction rate is first order in both periodate and amino acid, and the overall reaction follows second-order kinetics. The rates decrease with increase in [H']. A catalytic effect of the buffers was not observed in the oxidation process. An analysis of the dependence of the rate on [H'] reveals that the reactive species under the experimental conditions are periodate monoanion and dianion and the dipolar form of the amino acid. The mechanism proposed and the derived rate law are consistent with the observed kinetics. The rate constants predicted using the derived rate law are in agreement with the observed rate constants, thus justifying this rate law and hence the proposed mechanistic scheme.ROSA PASCUAL et MIGUEL A. HERRAEZ. Can. J. Chem. 63, 2349 (1985). Operant h 10°C et dans un milieu acide, on a CtudiC la cinCtique de l'oxydation de la sCrine et de la thrkonine par le periodate. La rkaction est du premier ordre tant en periodate qu'en acide aminC et I'ensemble de la rkaction est du deuxibme ordre. Les vitesses diminuent avec une augmentation de I'aciditt. On n'a pas observk d'effet catalytique des tampons sur les processus d'oxydation. Une analyse de la relation entre les vitesses de rkaction et la concentration en H' rCvble que les espkces rCactives dans ces conditions expkrimentales sont les monoanion et dianion du periodate et la forme dipolaire de I'acide aminC. Le mCcanisme proposC ainsi que I'Cquation de vitesse qui en dCrive sont en accord avec les cinCtiques observCes. Les constantes de vitesse que I'on peut prCvoir en se basant sur I'Cquation de vitesse que I'on a obtenu sont en accord avec les constantes de vitesses observ6es et ces rksultats justifient cette Cquation de vitesse et donc le schCma mtcanistique proposC.[Traduit par le journal]

ROSA PASCUAL, MIGUEL A. HERRAEZ, and EMILIO CALLE. Can. J. Chem. 67, 634 (1989).The kinetics of oxidation of proline by periodate has been studied at pH 1.40-8.83 and 30.0°C. The reaction rate is first order in both periodate and amino acid, and the overall reaction follows second-order kinetics. There was no evidence for the formation of an appreciable amount of intermediate. The reaction rate is highest at pH 4-7 and the oxidation is catalysed by HP@-ions. The pH dependence of the reaction rate can be explained in terms of reaction of periodate monoanion and the protonated and dipolar forms of the amino acid. The mechanism proposed and the derived rate law are consistent with the observed kinetics. The rate constants obtained from the derived rate law are in agreement with the observed rate constants, thus justifying the rate law and the proposed mechanistic scheme.Key words: oxidation of proline, oxidation by periodate.

ChemInform Abstract The highest reaction rate occurs at pH 4-7. CO2 and pyrrolidone-(2) form as products without intermediates. The oxidation is catalyzed by HPO42-ions. In view of proline as a constituent in some proteins, such as collagen, the results are of interest because the oxidation causes denaturation of proteins and inactivation of enzymes.