Intraluminal immunoreactive caseinomacropeptide after milk protein ingestion in humans

Abstract

Caseinomacropeptide (CMP)is a 64 amino acids peptide which is the first product released after kappa-casein hydrolysis. The present work investigates the kinetics delivery of CMP in human jejunal lumen during the digestion of intrinsically [15N]-labelled casein, whey protein, yoghurt and pea flour meal. Effluents were collected through a nasointestinal tube and analysed for the enrichment in [15N] to evaluate the dietary nitrogen fraction. Detection and quantification of CMP was performed by an inhibition Elisa procedure. No trace of CMP was detected in the ileum of volunteers after the ingestion of the casein meal. The results showed that CMP appears in the jejunal effluents within the first 20 min after meal ingestion at a level varying from meal to meal. During digestion of whey protein, CMP appeared rapidly as a single peak and in high amounts, whereas it is discharged slowly in moderate proportions with the casein meal. These results demonstrate that CMP is emptied from the stomach in significant amounts during milk products digestion and support the hypothesis that food-born peptides could exert a physiological function. Moreover, in the present study a relation could be assumed between the amount of CMP in the meal and the stimulation of luminal endogenous nitrogen secretion. However, the specific physiological activity of CMP in humans, particularly on the digestion process, requires further studies.

Kappacin, a Novel Antibacterial Peptide from Bovine Milk

“…The peptide released by natural digestion of casein in the stomach, with chymosin, CMP (11) has been shown to substantially inhibit the adherence of Streptococcus mutans to salivary pellicle (17,21,25,26), and this has been proposed to be the mechanism of anticariogenicity of milk protein fractions in animal caries models (7). In this study we have shown that CMP has growth-inhibitory activity against S. mutans and P. gingivalis as well as E. coli.…”

“…Earlier studies have shown that S. mutans will grow at pH 7.0 but not at lower pH values in the presence of the ionophore gramicidin, which collapses transmembrane cation gradients through formation of an anionic pore (3). CMP has been detected in the stomach, duodenum, and jejunum of humans after milk ingestion (11). The release of kappacin in the stomach therefore may be a mechanism to limit gastrointestinal tract infection in the developing neonate, by increasing the sensitivity of bacteria to gastric acid by collapsing essential transmembrane cation gradients.…”

Learnings from quantitative structure–activity relationship (QSAR) studies with respect to food protein-derived bioactive peptides: a review

“…Earlier studies have mainly relied on immunoreactive techniques (e.g., enzyme-linked immunoassay -ELISA) or Edman degradation of the Nterminal amino acids linked to peptide sequencers to identify positive peptide candidates. [5][6][7] However, advances in mass spectrometric (MS) analysis have allowed greater capability in the identication of peptides within complex mixtures and also identication of a large number of peptide sequences in an automated manner, for reviews, see: ref. [8][9][10][11].…”

Casein glycomacropeptide for active distal ulcerative colitis: a randomized pilot study

“…It constitutes approximately 20% of the whey protein fraction and is resistant to acid [7,8]. It constitutes approximately 20% of the whey protein fraction and is resistant to acid [7,8].…”