Fragmentation of porcine beta-lipotropic hormone with plasmin.

Porcine beta-lipotropic hormone was digested by plasmin and the fragments released were isolated and identified. Based on the structure and the yield of the plasmin fragments and also on the time-course of the digestion, the relative sensitivity of the theoretically susceptible bonds towards the action of plasmin was estimated. The Lys79-Asn80 bond was the most susceptible to plasmin, the Arg51-Trp52 and Arg60-Tyr61 bonds were split to a lesser extent than the Lys79-Asn80 bond, but much faster than the Lys46-Met47, Lys69-Ser70 and Lys84-Asn85 bonds of the beta-lipotropic homone structure. Further lysyl and arginyl bonds of the molecule were not attacked under our experimental conditions.