STUDIES ON CYSTINE IN WOOL

Abstract

1) It wasa found that phospho-tungstic acid (Wo), a reagent for the estimation of-SH groups, could be used as a colour reagent in the paper chromatography for mercapto or disulphide compounds.This reagent causes remarkable colourations on the paperchromatogram in the presence of-SH groups, and also by spraying sodium sulphite solution (Na2 SO3) followeing the Wo-spraying in the presence of -S-S- bonds.This method is profitable for ease of treatment and in sensitivity compared with the nitroprusside-cyanide method. When ninhydrin is used together on the same paper, this must be sprayed after Wo or Wo-Na2 SO3 spraying, otherwise the quantities to be detected of-SH groups or -S-S- bonds decrease in order to react between -SH groups and ninhydrin. In the presence of compound with -SH groups, the mixture of n-butanol, acetic acid and water for the developing solution brings the clear spots on the chromatogram than phenol solution does.2) Based on the above results, reactions between-SH groups and -S-S- bonds were further studied. Mixed disulphide (CY-S-S-TG) was, even without being oxidized by iodine, detected from the mixed solution of cysteine (CY-SH) and thioglycollic acid (TG-SH) which was kept at comparatively higher pH. In the same way, this compound was detected from the mixed solution of cystine (CY-S.) with TC-SH, and of CY SY. with dithiodiglicollic acid (TG-S-S-TG) respectively except at very low pH.The preciser result was obtained by means of combining those mixtures with dinitroflorobenzen, known as-SH blocking agent.Neither TG-SH nor TG-S-S-TGspot was detected when TG-SH solution was mixed with diazonium salt of sulphanilic acid. Two Wo-possitive spots which have lower Rf's than that of TG-SH were recognized in addition to TG-S-S-TG when TG-SH solution was mixed with sodium nitrite on acidic side.This method could also be applied to find sulphur compounds in the hydrolyzates of wool.