Mecanismos de absorção de aminoácidos e oligopeptídios. Controle e implicações na dietoterapia humana

Abstract

The mechanisms involved in the absorption of amino acids and oligopeptides are reviewed regarding their implications in human feedings. Brush border and basolateral membranes are crossed by amino acids and di-tripeptides by passive (facilitated or simple diffusion) or active (Na+ or H+ co-transporters) pathways. Active Na(+)-dependent system occurs mainly at brush border and simple diffusion at basolateral, both membranes have the passive facilitated transport. Free-amino acids use either passive or active transport systems whereas di-tripeptides do mainly active (H+ co-transporter). Brush border have distinctive transport system for amino acids and di-tripeptides. The former occurs mainly by active Na+ dependently whereas the later is active H(+)-dependent with little affinity for tetra or higher peptides. Free amino acids are transported at different speed by saturable, competitive carriers with specificity for basic, acidic or neutral amino acids. Di and tripeptides have at least two carriers both electrogenic and H(+)-dependent. The basolateral membrane transport of amino acids is mostly by facilitated diffusion while for di-tripeptides it is an active anion exchange associated process. The main regulation of amino acids and di-tripeptide transport is the presence o substrate at the mucosal membrane with higher the substrate higher the absorption. Di and tripeptides are more efficiently absorbed than free amino acids which in turns are better absorbed than oligopeptides. So di-tripeptides result in better N-retention and is particularly useful in cases of lower intestinal absorption capacity. The non-absorbed peptides are digested and fermented by colonic bacteria resulting short-chain fatty acids, dicarboxylic acids, phenolic compounds and ammonia. Short-chain fatty acid provides energy for colonocytes and bacteria and the ammonia not fixed by bacteria returns to the liver for ureagenesis.

Degree of hydrolysis and peptide profile of whey proteins using pancreatin

“…The amino acids can be absorbed either in the free form, by simple and facilitated diffusion (membrane transporters), or in the di-and tri-peptide form (oligopeptide transporters) (GILBERT; WONG; WEBB JUNIOR, 2008). Furthermore, according to Frenhani and Burini (1999), the di-and tripeptides are more efficiently absorbed than an equivalent mixture of free amino acids. Therefore, the enzymatic hydrolysis of proteins can improve their nutritional value by reducing the peptide size and releasing small peptides and free amino acids, which can be readily absorbed.…”

Action of a pancreatin and an Aspergillus oryzae protease on whey proteins: correlation among the methods of analysis of the enzymatic hydrolysates

“…The amino acids can be absorbed either in the free form, by simple and facilitated diffusion (membrane transporters), or in the di-and tripeptide form (oligopeptide transporters) (Gilbert et al 2008). Furthermore, according to Frenhani and Burini (1999), the di-and tripeptides are more efficiently absorbed than is an equivalent mixture of free amino acids. From a nutritional point of view, hydrolysates H3, H4 and H5, prepared using pancreatin, showed the best peptide profiles.…”

Hydrolysis of whey proteins by a Bacillus licheniformis protease

“…The AAs may be absorbed either in a free form, by simple or facilitated diffusion (membrane transporters), or as dipeptides and tripeptides (oligopeptide carriers) (GILBERT et al, 2008). Furthermore, according to Frenhani and Burini (1999), the dipeptides and tripeptides are more effi ciently absorbed than an equivalent mixture of free amino acids.…”