[Detection of peptide, an activator of cyclic nucleotide phosphodiesterases, in uterine tissue]

The soluble fraction of uterine tissue was found to contain a factor which is a potent activator of various cyclic nucleotide phosphodiesterases (with the exception of the retinal photoreceptor cell enzyme). The protein origin of this factor was established, using proteolysis, precipitation with trichloroacetic acid. The activator was purified by gel filtration on Sephadex G-25 and Biogel P-4 as well as by a highly effective liquid chromatography. The activator was shown to be a peptide with Mr = 1150 Da. The peptide was thermostable and stable within a broad range of pH. Besides phosphodiesterases, the peptide activated 5'-nucleotidase and Mg2+-ATPase of photoreceptor membranes.