ABSORPTION OF INTACT PEPTIDES: STUDIES ON TRANSPORT OF PROTEIN DIGESTS AND DIPEPTIDES ACROSS RAT SMALL INTESTINE <i>IN VITRO</i>

Gardner, Michael L. G.

doi:10.1113/expphysiol.1982.sp002682

Cited by 34 publications

(17 citation statements)

References 29 publications

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“…However, the respective Ki values, 10-6 and 6-2 mm, were considerably higher than the measured Km (0 49 mM) for L-lysine. It is now well established that the gut may transport intact peptides, although the transport systems appear to be separate from those for amino acids (Cheeseman & Parsons, 1976;Burton, James, Smith & Young, 1980;Gardner, 1982). In the rat blood-brain barrier, peptide formation prevents either L-leucine or L-phenylalanine from being transported via the system L (Zlokovic, Begley & Chain, 1983).…”

Section: Discussionmentioning

confidence: 99%

Characteristics of a cationic amino acid transport system in the basolateral membrane of the cat salivary epithelium.

Mann¹,

Wilson²,

Yudilevich³

1984

The Journal of Physiology

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SUMMARY1. The specificity and kinetics of L-lysine influx across the basolateral surface of the cat salivary epithelium have been investigated in the perfused cat submandibular gland using a high-resolution, paired-tracer dilution technique.2. L-lysine influx was measured at several different perfusate concentrations (0-05-2-5 mM) and was found to be saturable. A Michaelis-Menten analysis based on a single entry site gave a Km of 0 49 + 0-08 mm and a Vmax of 231 + 20 nmol/min. g.3. The uptake of L-lysine was highly stereospecific and markedly inhibited by L-arginine (0-25-2-5 mM). The inhibitor constant (Ki) was 0-23 mm, suggesting that the carrier had a greater affinity for L-arginine than L-lysine. 4. When the inhibitory effects of L-histidine (0-5-10 mM) were examined the K1, estimated at 10 mm, was 4-6 mm. Nine other neutral amino acids (L-alanine, L-serine, L-cysteine, glycine, L-proline, L-homoserine, L-leucine, L-phenylalanine and Lglutamine), and an acidic amino acid (L-aspartate) were also tested at 10 mm and, although several caused inhibition, the Ki was always at least 20 times higher than the measured Km for L-lysine. It is concluded the carrier is highly specific for the L-form of the basic amino acids. 5. The sodium dependence ofL-lysine influx was investigated over a range ofL-lysine concentrations (0 05-1 mM), and total removal of sodium from the perfusate had no effect on L-lysine influx.6. In the presence of sodium, L-homoserine, an amino acid not normally present in animal tissues, inhibited L-lysine influx (Ki = 13 mM). This inhibition was not observed in the absence of sodium, and contrasts with the observation that the inhibitory action of L-histidine was sodium independent. 7. The present data suggest that a specific cationic amino acid transport system is operative in the basolateral membrane of the cat salivary epithelium. The properties of this system appear to be similar to the system y+ which has been described in several other cell types. E. MANN, S. M. WILSON AND D. L. YUDILEVICH

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Section: Discussionmentioning

confidence: 99%

Characteristics of a cationic amino acid transport system in the basolateral membrane of the cat salivary epithelium.

Mann¹,

Wilson²,

Yudilevich³

1984

The Journal of Physiology

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“…The methods for investigation of peptide absorption were essentially those previously used by Gardner [9][10][11]. The amino acid compositions of the serosal fluid and the intestinal mucosa analyzed before the hydrolysis indicated the uptake of peptides as free amino acids.…”

Section: Methodsmentioning

confidence: 99%

“…The amino acid compositions of the serosal fluid and the intestinal mucosa analyzed before the hydrolysis indicated the uptake of peptides as free amino acids. Peptide-N was estimated as bound-N by the difference method, i.e., from the the increase in free amino acid on acid hydrolysis [10][11][12]. Intact transport was calculated as follows:…”

Section: Methodsmentioning

confidence: 99%

“…These data suggest that absorption of di-and tripeptides would be more rapid than that of large peptides consisting of penta-or hexapeptides, and that intact transport of peptides would be greater for transport of di-and tipeptides. When absorption of casein and casein hydrolysate was studied, the differences between the effects of casein and casein hydrolysate were considered to depend on the rate of protease digestion, since casein should be hydrolyzed by pancreatic enzymes [18].…”

Section: Effects Of Cpm On Mucosal Parametersmentioning

confidence: 99%

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Effect of Peptide Chain Length on Absorption and Intact Transport of Hydrolyzed Soybean Peptide in Rat Intestinal Everted Sac.

Chun

Sasaki

Fujiyama

et al. 1996

J. Clin. Biochem. Nutr.

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SummaryIn this study using everted sacs of rat jejunum, we investigated the difference in absorption of two types of soybean peptides (small peptide: SP, and large peptide: LP). We investigated the influence of peptide length on absorption and intact transport of hydrolyzed soybean peptides. The everted sacs were incubated for S or 10 min in bicarbonate-saline buffer containing a 1% (w/v) concentration of each soybean peptide. After the incubation, the amounts of free amino acids and peptides that were transported to the serosal fluids and the mucosa were measured with an automatic amino acid analyzer both before and after the hydrolysis of the serosal fluids and mucosa. The results indicated that SP was absorbed more rapidly than LP and that the more rapid absorption of SP was due to the greater intact transport of SP. When the everted sacs were made from jejunum that had been injured by intraperitoneal injection of cyclophosphamide (300 mg/kg), no significant differences were noted between the absorption of SP and that of LP. We also ascertained that an aminopeptidase inhibitor (bestatin) decreased the aminopeptidase activities of the rat jejunum. In the presence of 1 X 10_4 M bestatin in the incubation buffer, no significant differences were noted between the absorption of SP and that of LP. We conclude that SP is absorbed more rapidly than LP in normal rat jejunum due to greater intact transport.

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“…There has been no evidential study, however, on absorption of small bioactive peptides in the human circulating blood system due to lack of a sufficient assaying method. Studies on peptide transport through membranes have demonstrated that an intestinal absorption of peptide was faster than that of its individual amino acids by jejunal perfusion tests in rat 7,8) and in human. 9,10) According to the reports on the peptide transport system at the intestinal membrane, 11,12) some peptide transporters were identified or cloned as human PepT1 and T2, 11) and a more preferable structure of absorbed peptides or peptidic drugs was found to be di-/tripeptides possessing a free terminal carboxyl group and at least one peptide bond.…”

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confidence: 99%

Absorption of Val-Tyr with in Vitro Angiotensin I-Converting Enzyme Inhibitory Activity into the Circulating Blood System of Mild Hypertensive Subjects.

Matsui

Tamaya

Seki³

et al. 2002

Biological & Pharmaceutical Bulletin

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ABSORPTION OF INTACT PEPTIDES: STUDIES ON TRANSPORT OF PROTEIN DIGESTS AND DIPEPTIDES ACROSS RAT SMALL INTESTINE IN VITRO

Cited by 34 publications

References 29 publications

Characteristics of a cationic amino acid transport system in the basolateral membrane of the cat salivary epithelium.

Characteristics of a cationic amino acid transport system in the basolateral membrane of the cat salivary epithelium.

Effect of Peptide Chain Length on Absorption and Intact Transport of Hydrolyzed Soybean Peptide in Rat Intestinal Everted Sac.

Absorption of Val-Tyr with in Vitro Angiotensin I-Converting Enzyme Inhibitory Activity into the Circulating Blood System of Mild Hypertensive Subjects.

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