Detection of prosaposin and mature saposins in goat milk

Increased scientific knowledge related to the nutritional, functional and biological activities and health benefits of goat milk is needed to further promote goat farming, goat milk and traditional or innovative neutraceuticals as a basis for socio-economic benefit. Identification and characterization of milk derived Prosaposin is essential to development of neutraceuticals from goat milk that maybe beneficial to human health. The objectives of this study were to detect Prosaposin and its mature proteins in milk from different breeds of goats. Raw milk was collected from eight different breeds of goat. Whey fractions were separated by high speed centrifugation. Extracts were analyzed by electrophoresis using the Pharmacia Phastsystem (GE Healthcare) in 12.5% homogeneous gels. Gels were silver stained to analyze total protein. Phastsystem diffusion immunoblotting with HRP enzyme-labeled polyclonal anti-Prosaposin, anti-saposin and a tetramethylbenzidine substrate was used to identify specific proteins. Multiple proteins were observed in whey fractions from all animals tested. Antibodies detected a 70-65 kDa Prosaposin band and a 12-14 kDa saposin C band in all goat breeds. Both Prosaposin and its derivative saposin A, B, C and D were detected in caprine milk. These studies show that Prosaposin is present in milk from different breeds of goats contributing to therapeutic attributes of goat milk. The biological activity of saposins such as the neurotrophic activity of goat saposin C need further characterization.