Instability studies of porcine somatotropin in aqueous solutions and the possible reagents for its stabilization

The instability of porcine somatotropin (pST) in various solutions and possible stabilization of the hormone by sugars and mild detergents were studied. Aggregation and decomposition of the hormone molecules in various pH solutions and under presence of sugar or detergent were monitored by gel permeation chromatography (GPC) or ultraviolet spectroscopy (UV). The pST is a very unstable hormone in an aqueous environment. It was found in this project that the peptide hormone underwent aggregation or decomposition quickly in acidic and alkaline solutions but slowly in neutral pH solutions. High losses of PST monomers were seen in concentrated solutions of the hormone. On the other hand, PST monomers were stabilized to a certain degree in glucose solutions and at a low concentration of urea. These results should facilitate the development of efficient controlled release systems which are essential for commercializing porcine somatotropin.