Rates of Absorption by rat Intestine of Pancreatic Hydrolysates of Proteins and Their Corresponding Amino Acid Mixtures

Crampton, R. F.; Gangolli, S.D.; Simson, Pamela; Matthews, D. M.

doi:10.1042/cs0410409

Cited by 52 publications

(21 citation statements)

References 11 publications

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“…It suggests that much of the Ala is produced by a direct reaction between Asp and pyruvic acid: Asp+Pyruvic 0 xalocetic acid + Ala, although no single transaminase catalysing such a reaction has been identified (Sallach & Fahien, 1969). The present results, which show that mucosal uptake of amino acids is more rapid from many dipeptides than from the equivalent amino acid mixtures, help to explain more fully the observation that tryptic hydrolysates of proteins, consisting largely of small peptides, are absorbed more rapidly than the corresponding amino acid mixtures (Crampton, Gangolli, Simson & Matthews, 1971) and the fact that proteins are absorbed much more rapidly than would be expected if they had to undergo complete hydrolysis to amino acids in the intestinal lumen (Fisher, 1954;Crane & Neuberger, 1960).…”

Section: Discussionmentioning

confidence: 58%

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

Burston¹,

Addison²,

Matthews³

1972

Clinical Science

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1. The characteristics of transport and hydrolysis of twenty-two dipeptides containing basic and acidic amino acids by rat ileal rings were investigated in vitro. The peptides included combinations of basic and neutral, basic and basic, basic and acidic, acidic and acidic, and acidic and neutral amino acids.2. All peptides studied were removed intact from the bulk phase of the incubation medium, though, in general, only free amino acids appeared in the tissue. Uptake of one or both constituent amino acids was greater from the peptide than from the equivalent amino acid or amino acid mixture in the case of at least one peptide from each group and in eighteen of the twenty-two peptides studied. In general, there was no relationship between the extent of uptake of amino acids from peptides and the extent of their hydrolysis by the system. The results support the hypothesis that there is more than one mode of uptake of amino acids from peptides.3. Hydrolysis of y-glutamyl-L-glutamic acid by intact intestine or intestinal homogenate was slight, and intact peptide was taken up by the tissue. Uptake of free glutamic acid from this peptide was poor. Comparison of y-glutamyl-L-glutamic acid with three other slowly hydrolysed dipeptides, glycyl-D-valine, sarcosylglycine and glycylsarcosine, suggested that all four were transported into the mucosal cells and hydrolysed intracellularly. The results indicate that the presence of a y-linkage or a D-amino acid, or methylation of the free amino group as in sarcosylglycine, impair both transport and hydrolysis of peptide, but that attachment of a methyl group to the N of the peptide bond, as in glycylsarcosine, impairs hydrolysis but has no effect on peptide transport. 4. L-Aspartic acid and L-glutamic acid were extensively transaminated by the intestine, whether presented as free amino acids or in peptides. Evidence was obtained suggesting that production of alanine from aspartic acid resulted from direct transamination of aspartic acid with pyruvic acid, rather than from a sequence of two reactions involving aspartate and alanine aminotransferases.

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Section: Discussionmentioning

confidence: 58%

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

Burston¹,

Addison²,

Matthews³

1972

Clinical Science

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“…Enzymic digestion of proteins before feeding has resulted in poor performance (Cunningham & Brisson, 1957;Pettigrew et al 1977). However, the extent of protein hydrolysis was not measured by these workers and, as mentioned previously, mixtures of small peptides are absorbed more rapidly than mixtures of free amino acids (Crampton et al 1971 ;Matthews et al 1968). Seve et al (1975) gave hydrolyzed fresh fish to pigs from 12 d of age.…”

Section: Discussionmentioning

confidence: 99%

Digestion in the pig between 7 and 35 d of age 6. The digestion of hydrolyzed milk and soya-bean proteins

Leibholz

1981

Br J Nutr

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I. Four pelleted diets were prepared containing milk or isolated soya-bean protein (ISP) as the major protein source. The milk and ISP were given either as intact proteins or partially (0.65) hydrolyzed with papain before feeding.2. The diets were given ad li.5. to thirty-two pigs from 7-28 d of age. The pigs were slaughtered at 28 d of age. 3. Weight gains, food conve::sion ratios and nitrogen balances of pigs given diets containing milk protein were better than those of diets containing ISP (231 g/d, 0.80 and 11.5 g/d compared to 209 g/d, 0.88 and 9.00 g/d respectively). 4. Partial hydrolysis of proteins before feeding did not affect the performance of the pigs. 5. Apparent digestibilities of N before the ileum and in the whole tract were 0.78 and 0.94 for the pigs given 6. Retention time of ISP die:s in the whole digestive tract was 1475 min and that of the milk-protein diets was 7. pH of digesta in the stomach was 5.0-5.3 for all diets and increased to 6.9-7. I in the ileum. 8. There were no differences in flows of total N and protein N to the ileum and lower digestive tract between 9. Apparent absorptions of N in the stomach, duodenum and jejenum were greater in the pigs given diets 10. Flows of total N and protein N to the ileum tract were greater when the pigs were given the 11. Hydrolysis of proteins before feeding resulted in a reduced trypsin and chymotrypsin activity in the 12. Retention of dietary N i.1 the carcass was greater in pigs given the milk-protein diets (0.79) than in those the ISP diets and 0.86 and 0.97 for the pigs given the milk-protein diets.1089 min.the pigs given the intact-and hydrolyzed-protein diets.containing hydrolyzed proteins than in those given diets containing the intact proteins.ISP diets than when they were given the milk-protein diets.duodenum and pancreas.given the ISP diets (0.68).Numerous experiments (Hays et al. 1959;Maner et al. 1961 ;Wilson & Leibholz, 1981 a) have shown that the performance of pigs given soya-bean meal, soya-bean flour or isolated soya-bean protein (ISP) was inferior to that of pigs given milk proteins between 7-28 d of age. The young pig has ii limited capacity to secrete pepsin and acid, and this increases with age (Cranwell, 1977) arid the proteinase activity of the pancreas also increases with age (Coring et al. 1978). It has been shown (Wilson & Leibholz, 1981c), that 46% of the nitrogen in the small intestine of 28-d-old pigs given soya-bean proteins was precipitated by trichloracetic acid ('TCA) while only 24% of the N was precipitated in the pigs given milk protein.It appeared possible that the growth of pigs given soya-bean proteins was limited by the hydrolysis of the protein in the intestines. The present experiment was designed to study the performance of pigs fed on normal milk and soya-bean proteins and the same products hydrolyzed before feeding. E X P E R I M E N T A L

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“…Recently it has become clear that a large proportion of those small peptides which have been investigated can also be absorbed, and that under certain circumstances at least some amino acid residues may be absorbed more rapidly from tri-and di-peptides than from the free amino acid (e.g. Newey & Smyth, 1959; Asatoor, Cheng, Edwards, Lant, Matthews, Milne, Navab & Richards, 1970;Matthews, Craft, Geddes, Wise & Hyde, 1968; Crampton, Gangolli, Simson & Matthews, 1971 Silk, Clark, Marrs, Addison, Burston, Matthews & Clegg, 1975). The fate of a balanced mixture of amino acids and peptides, as in a natural digest of a first class protein or its equivalent, may be quite different from that of single amino acids or peptides.…”

Section: Introductionmentioning

confidence: 99%

Absorption of amino acids and peptides from a complex mixture in the isolated small intestine of the rat.

Gardner¹

1975

The Journal of Physiology

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SUMMARY1. Amino acid and peptide absorption from a pancreatic digest of casein at low concentration by an isolated preparation of perfused rat small intestine has been measured.2. The rate of absorption of each amino acid (free or peptide-bound) is closely proportional to its concentration in the perfusate; this implies a constant Vmax/Km ratio for all amino acids in the mixture.3. There is a high correlation between the compositions of luminal perfusate and secretion into the tissue fluid (apart from the content of glutamic and aspartic acids and alanine).4. The concentrations of each free amino acid are, on average, 9 times as great in secretion as in lumen; the total peptide-N concentration in secretion is approximately 4 times that in the lumen.5. The rate of absorption of each free amino acid is highly negatively dependent on the rate of absorption of that amino acid in peptide-bound form, in addition to being positively dependent on the perfusate concentration of free amino acid.6. While peptide-bound proline appears to be well absorbed, free proline liberated by hydrolysis appears to pass back into the lumen as well as into the tissue fluid. Substantial back flux of hydrolysis products may occur for all amino acids.7. About one-third of the amino acids appearing in the secretion on to the serosal surface are peptide-bound.8. The rate of absorption of peptides appears to determine the rate of their hydrolysis which probably occurs mainly after entry into the mucosal cells.

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Rates of Absorption by rat Intestine of Pancreatic Hydrolysates of Proteins and Their Corresponding Amino Acid Mixtures

Cited by 52 publications

References 11 publications

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

Digestion in the pig between 7 and 35 d of age 6. The digestion of hydrolyzed milk and soya-bean proteins

Absorption of amino acids and peptides from a complex mixture in the isolated small intestine of the rat.

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