Purification of canine prolactin by preparative isotachophoresis

Preparative isotachophoresis in polyacrylamide gel using carrier ampholytes as 'spacers' has been used to purify prolactin from canine pituitary extracts. Using Ampholine pH 5-8 as spacers, a prolactin fraction was obtained which was essentially homogeneous as judged by the criteria of disc electrophoresis and isoelectric focusing. Amino acid analysis indicated a close similarity between canine and ovine prolactin. A growth hormone fraction, identified by its electrophoretic mobility, was also obtained although this was heterogeneous in disc electrophoresis at alkaline pH.