Protein digestion and amino acid and peptide absorption.

Although it has become clear that brush-border hydrolysis, and consequent utilization of the monosaccharide transport system, is the predominant method of absorption of the luminal products of carbohydrate digestion in man, it now appears certain that two major mechanisms are involved in the absorption of the luminal products of protein digestion: ( I ) transport of liberated free amino acids by group specific active amino acid transport systems, and (2) uptake of unhydrolysed peptides by mechanisms independent of the specific amino acid entry mechanisms.