On the preparation of highly purified slow reacting substance of anaphylaxis (SRS-A) from biological extracts

1 Very highly purified (greater than 100,000 u/mg) slow reacting substance of anaphylaxis (SRS-A) has been prepared by reversed phase high pressure liquid chromatographic (HPLC) techniques. 2 High resolution liquid chromatography suggests that SRS-A may exist in at least three distinct forms which are possible tautomeric. 3 SRS-A collected by antigen challenge in vivo and by calcium ionophore-induced release in vitro are chromatographically indistinguishable. 4 Treatment of SRS-A with diazomethane but not sodium borohydride results in a loss of biological activity but treatment of the methyl ester with base results in a partial recovery of activity. 5 Highly purified SRS-A was examined by infrared and ultra-violet spectroscopy, and found to have a benzene-aromatic and probably an amino acid.