Animal collagenases: specificity of action, and structures of the substrate cleavage site

Two separable hormone entities have been found by exploratory purifications and assay for release of growth hormone (GH) by radioimmunoassay. In recognition of frequent multiple activities of peptide hormones, these two hormonal entities are provisionally designated factors A-GHRH and B-GHRH until they are chemically characterized and their dominant functionality clarified. The A- and B-GHRH designations merely define the assay guiding isolation. Factor A-GHRH was found by filtration on Bio-Gel P-2, and purified over Sephadex G-25 in two partition chromatographic systems, and by Sephadex LH-20. The two partitions and stage LH-20 also differentiated the two active entities. Fractions of A-GHRH were active at 100–200 μg. Factor A-GHRH is inhibited by somatostatin.