Peptide production as fusion protein in transgenic mammal milk

Abstract

Peptides can be produced in and purified from the milk of transgenic animals. The peptides are made as fusion proteins with a suitable fusion partner such as &agr;-lactalbumin, which is a natural milk protein. The fusion partner protein acts to promote secretion of the peptides and, at least in the case of &agr;-lactalbumin, allows a single-step purification based on specific affinity. The peptide is released from the purified fusion protein by a simple cleavage step and purified away from the now liberated &agr;-lactalbumin by repeating the same affinity purification method. A particular advantage of producing peptides via this route, in addition to the obvious advantages of high yield and biocompatibility, is that specific post-translational modifications, such as carboxy terminal amidation, can be performed in the mammary gland.