Structure of slow-reacting substance of anaphylaxis (SRS-A)

To elucidate the chemical structure of slow-reacting substance of anaphylaxis from rat (SRS-A rat), SRS-A rat were purified by the method of Orange with modification using DEAE-Sephadex A-25 chromatography. Ultraviolet absorption spectrum of purified SRS-A rat indicated the presence of conjugated triene. Arylsulfatase B degradation products and HCl degradation products were subjected to analysis by a gas chromatography and mass spectrometry and a thin layer chromatography. Products obtained by arylsulfatase b catalysis contained 5,6-dihydroxy-7,9,11,14-eicosatetraenoic acid. HCl degradation products showed the presence of glycine, glutamic acid and cysteic acid. Furthermore, the analysis of anhydrous hydrazine degradation products of SRS-A rat and of HCl hydrolyzed products of dinitrophenylated SRS-A rat revealed the presence of glycine at C-terminal and glutamine acid at N-terminal. The study of the substrate specificity of arylsulfatase B against various materials including SRS-A rat suggested the presence of sulfone in SRS-A rat. The molecular ion peak of SRS-A rat sodium salt was observed at m/e 680 in field desorption mass spectrum of SRS-A rat. On the basis of these data, we identified the structure of SRS-A rat as [gamma]glutamyl-4(5-hydroxy-7,9,11,14-eicosatetraenoic acid-6-yl)-4,4-dioxyocysteinyl] glycine.