ROLE OF METAL FERROCYANIDES IN CONVERSION OF CYSTEINE TO CYSTINE

Abstract

Minerals adsorb more amino acids with charged R-groups than amino acids with uncharged R-groups. Thus, the peptides that form from the condensation of amino acids on the surface of minerals should be composed of amino acid residues that are more charged than uncharged. However, most of the amino acids (74%) in today's proteins have an uncharged R-group. One mechanism with which to solve this problem is the use of metal-ferrocyanides over the two pH values (pH-3 and pH-7) used in these experiments, the R-group of is positive for cysteine (cys) at pH-3 and negative at pH-7. Transition metal-ferrocyanides are important materials due to their wide application in the area of catalysis, magnetic material etc. These metal-ferrocyanides were prepared by the double decomposition method under specific conditions. Their characterization was done using XRD, TGA-DTA,. and FTIR analysis. Present study involves the adsorption of cysteine on metal ferrocyanides (iron-, cobalt-, nickel-, copper-, and zinc-ferrocyanides) and their study using FTIR-spectroscopy and X-ray diffractometry. The two main findings of study are: - First, after the cysteine adsorption, the FTIR spectroscopy and X-ray diffractometry data showed the formation of cystine. Second, when compared to other metal-ferrocyanides, iron-ferrocyanide adsorbed significantly more cysteine. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the metal-ferrocyanides and the amine and carboxylic groups are involved in this interaction. X-ray diffractometry showed no changes on metal-ferrocayides mineralogy and the following precipitated substances were found along with the metal-ferrocyanides after drying the samples: cysteine and cystine.