Trypsin-like nature of the pancreatic factor that corrects vitamin B12 malabsorption associated with pancreatic dysfunction.

Hog pancreas was subfractionated and assessed for its ability to correct vitamin B(12) malabsorption in patients with pancreatic dysfunction and in rats with partial pancreatic extirpation. The constituent obtained from the pancreas that increased vitamin B(12) absorption in both humans and rats was soluble at 50,000 g, heat labile, acid stable, and approximately 20,000-25,0000 in molecular weight. The active subfractions contained tryptic and chymotryptic but no amylase or lipase activity. Thrice-crystallized trypsin corrected the vitamin B(12) malabsorption in both patients with pancreatic insufficiency and in rats with subtotal pancreatectomy. These data indicate that pancreatic proteolytic enzymes-in particular, trypsin-are necessary for optimal vitamin B(12) absorption.