Appearance of Di‐ and Tripeptides in Human Plasma after a Protein Meal Does Not Correlate with PEPT1 Substrate Selectivity

• Published in: Molecular nutrition & food research Vol. 63; no. 5; pp. e1801094 - n/a
• Main Authors: Rohm, Florian, Skurk, Thomas, Daniel, Hannelore, Spanier, Britta
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-03-2019
• Subjects: Abundance; Adult; Amino acids; Amino Acids - blood; Animals; Anserine - blood; Biological properties; Biological samples; Biomarkers - blood; Blood plasma; Carnosine - blood; Chickens; Cross-Over Studies; Diet; Dietary Proteins - administration & dosage; Dietary Proteins - pharmacokinetics; Dipeptides - blood; Female; Healthy Volunteers; Humans; Kinetics; Male; Meat; Oryza; peptidases; Peptide transporter; peptide transporter 1; Peptide Transporter 1 - metabolism; Peptides; Peptides - blood; Peripheral blood; Plasma; Polarity; Postprandial Period; Poultry; protein digestion; Proteins; Quantitative analysis; Selectivity; Substrate Specificity; Substrates; Tandem Mass Spectrometry; protein digestion; peptide transporter 1; peptide transporter; amino acids; peptidases
• ISSN: 1613-4125; 1613-4133
• DOI: 10.1002/mnfr.201801094

Scope
Peptide transporter 1 (PEPT1) function is well understood, yet little is known about its contribution toward the absorption of dietary amino acids in the form of di‐ and tripeptides. In the present human study, changes in plasma concentrations of a representative oligopeptide panel are investigated after meat intake.
Methods and results
Based on a method for quantitative analysis of a panel of selected di‐ and tripeptides in biological samples, the kinetics of plasma changes of peptides derived from a widely accessible dietary protein source are described. The findings demonstrate postprandial changes of a whole spectrum of dipeptides of different size, charge, and polarity in peripheral blood in a dose‐dependent manner after consumption of chicken breast in healthy human volunteers. Although the substrate specificity of PEPT1 is well known, the spectrum of peptides appearing in blood cannot be matched to the affinity to PEPT1. Stability against hydrolysis by exo‐ and endopeptidases appears to be another factor influencing their presence in blood. In addition, the study shows that dipeptides, including gamma‐glutamyl‐peptides, as well as tripeptides are common components present in human plasma.
Conclusion
Besides amino acids, human peripheral blood contains numerous di‐ and tripeptides. The dietary source determines their abundance and composition.
Little is known about the ratio of amino acids and peptides and the types of peptides appearing in blood. A method is developed for the measurement of a representative panel comprising about 20 peptides, which shows that small peptides are “normal constituents” of human plasma with an individual dose‐dependent kinetic after protein intake.