THE DETERMINATION OF SULFHYDRYL GROUPS 



OF PROTEINS BY MEANS OF THE INHIBITORY-INDICATOR 



(BROMOACETYLNITRO-BENZOIC ACID) METHOD 



I. B. KRASNOV 



Laboratory of Histochemistry, Institute of Brain Research Academy 

 of Médical Sciences of USSR 



Most of the reactive agents used for developing the sulfhydryl groups re- 

 quire for dissolution the présence of spirit in the reactionary médium. The 

 concentration of spirit in the reactionary médium is such that produces 

 the denaturation of proteins and therefore the reactive agents mentioned 

 above cannot be used in conditions of a physiological experiment. This 

 can also be applied to histochemical reaction for the détermination of 

 SH-groups which are founded on the formation of mercaptides. As a resuit 

 of it moreover, compoundsare formed which are not firmly connected. There 

 arose a necessity of creating a reactive agent which cou»d be dissolved 

 in an aqueous médium and could react which sulfhydryl groups specifical- 

 ly and irreversibly at physiological figures of pH. Bromoacetylnitroben- 

 7.oic acid first syntesised and described by us bas ail thèse properties. 

 The use of solutions of bromoacetylnitrobenzoic acid prepared on the so- 

 lution of Ringer-Locke or Tyrode makes it possible when registering, the 

 physiological conditions of the investigated tissue and successive histo- 

 chemical treatment clearly to define the localisation of SH-groups respon- 

 sible for the rise of physiological effects. An investigation of the locali- 

 sation of SH-groups of réceptive proteins of ganglion cervical superior of 

 the cat bas been carried out. The possibility of the use of bromoacetylni- 

 trobenzoic acid for the spécifie development of sulfhydryl groups of pro- 

 teins in the conditions of usual histochemical investigation as well as of 

 the quantitative détermination of SH-groups of tissue proteins which can 

 be dissolved in water bas been shown. 



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