Prionex?, a very effective BSA alternate, is a 10% aqueous solution of a polypeptide fraction of highly purified dermal collagen of porcine origin. It has excellent protein stabilizing properties. Prionex? is prepared by partial hydrolysis and is terminally sterilized. It is free from cartilage, bone and plasma components and is therefore a pure form of partially hydrolyzed gelatine type A.