Disulfide形Thiamine誘導体(第10報) : Disulfide形ThiazoliumとL-Cysteineの交換反応

概要

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In order to clarify the characteristics of the reactivity of thiamine derivatives of disulfide type, the exchange reaction rate between bis[2-(N-phenethyl formamido)propenyl] disulfide and cysteine was compared with the reactions between thiamine derivatives of disulfide type and cysteine, Following results were obtained : 1) The reaction was carried out to form 4-methyl-3-alkyl thiazolium. 2) The reverse reaction was not observable below neutral pH. The rate constant k_1 was calculated from the formation of 4-methyl-3-alkyl thiazolium below pH 7 ; the rate constant k_1 was : 3.88×10^4 liter mole^<-1> min^<-1> and 11.1 kcal mole^<-1> was the activation energy. 3) The reverse reaction was observed above neutral pH. 4) It was concluded that the exchange reactions between cysteine and thiazolium derivatives of disulfide type including thiamine derivatives of disulfide type depend on the ring opening-closing reaction of thiazolium nucleus and can be expressed as follows : At pH≪pK_a of thiazolium ThiaSSThia+CyS^-→ThiaSSCy+ThiaS^- ThiaSSCy+CyS^-→cystine+ThiaS^- ThiaS^-→thiazolium At pH≫pK_a of thiazolium ThiaSSThia+CyS^-⇄ThiaSSCy+ThiaS^- ThiaSSCy+CyS^-⇄cystine+ThiaS^-
公益社団法人日本薬学会の論文
1970-04-25