[Isolation, purification and structure of molecules of a vasoactive component from rabbit skeletal muscle]

A low molecular weight factor with pronounced vasoactive properties has been isolated from rabbit muscle. The procedure for lyophilized tissue extract purification included fractional methanol extraction with subsequent column chromatography on TSK-GEL Toyopearl, DEAE-Toyopearl 650 ion-exchanger and Sephadex G-10. The resulting preparation was homogeneous as evidenced from reversed phase HPLC. The structure of the factor was examined by using UV- and IR-spectrophotometry as well as by PMR and 13C-NMR. It was found that the vasoactive factor includes an inosine nucleotide structure covalently bound to a di- or tri-alanine peptide while the phosphate group is free. It is suggested that the binding of the peptide to the inosine moiety occurs via a C-terminal carboxyl of the peptide and pentose hydroxyls. It seems probable that the vasoactive effect is a result of esterification of the purine nucleotides with the peptide.