Intestinal Transport of a Tetrapeptide, l-Leucylglycylglycylglycine, in Rat Small Intestine in Vivo

1979 ◽  
Vol 57 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Y. C. Chung ◽  
D. B. A. Silk ◽  
Y. S. Kim
Keyword(s):  
Amino Acid ◽  
Brush Border ◽  
Transport Mechanism ◽  
Intestinal Transport ◽  
General Mechanism ◽  
Aminopeptidase Activity ◽  
Amino Acid Mixtures ◽  
Jejunal Perfusion

1. The intestinal transport mechanism for the tetrapeptide l-leucylglycylglycylglycine, Leu-Gly-Gly-Gly, and its relation to the transport of free Leu, Leu-Gly and Leu-Gly-Gly were investigated in vivo by means of jejunal perfusion in rats. 2. The rates of net Leu absorption from peptides (Leu-Gly and Leu-Gly-Gly-Gly) were significantly greater than those from the free amino acid mixtures when the test solutions were perfused at a concentration of 15 mmol/l. 3. Net Leu absorption rates from Leu-Gly (10 μmol/ml) and Leu-Gly-Gly (10 μmol/ml) were extensively inhibited (84% and 68% respectively) by Gly-Pro at 100 mmol/l, whereas Gly-Pro had no effect on Leu absorption from Leu-Gly-Gly-Gly. l-Alanine (Ala, 100 μmol/ml), on the other hand, which completely inhibited Leu absorption during perfusion of free Leu, inhibited Leu uptake from Leu-Gly-Gly-Gly only about 50% at all concentrations studied. Ala had no effect on Leu absorption from Leu-Gly and Leu-Gly-Gly (10 μmol/ml). 4. Neither Ala at 100 μmol/ml nor Gly-Pro at 100 μmol/ml had any effect on brush-border aminopeptidase activity in vitro, suggesting that the hydrolytic capacity of the intestinal mucosal brush border was unaltered when Ala or Gly-Pro was included in the perfusion mixture. l-Alanyl-β-naphthylamide (20 μmol/ml), which inhibited brush-border aminopeptidase activity by 85% in vitro, failed to block substantially net Leu absorption from Leu-Gly and Leu-Gly-Gly-Gly. 5. The data presented suggest that, although some of the Leu from the tetrapeptide, Leu-Gly-Gly-Gly, may be hydrolysed before transport, nearly 50% of the tetrapeptide appears to be transported intact. Although Leu-Gly, Leu-Gly-Gly and Gly-Pro seem to share a common transport mechanism, the system used for intact Leu-Gly-Gly-Gly absorption seems to be distinct. However, the present study does not exclude the possibility that binding of the tetrapeptide to the brush-border aminopeptidase alters the affinity of Leu for the amino acid carrier, and therefore further studies are necessary before firm conclusions can be made on the general mechanism of tetrapeptide transport.

“In vivo” amplification of biological activity of tetragastrin by amino acid hydroxamates

1984 ◽  
Vol 4 (12) ◽  
pp. 1009-1015 ◽  
Author(s):  
J. P. Bali ◽  
H. Mattras ◽  
A. Previero ◽  
M. A. Coletti-Previero
Keyword(s):  
Biological Activity ◽  
Amino Acid ◽  
Aromatic Amino Acid ◽  
Aminopeptidase Activity ◽  
Proteolytic Degradation ◽  
Short Peptides ◽  
Rat Blood ◽  
Active Peptides

Rat blood was shown to contain an aminopeptidase which rapidly hydrolyses short peptides containing an aromatic amino acid as N-terminal residue. Using tetragastrin (Trp-Met-Asp-PheNH 2) as substrate, we showed that some amino acid hydroxamates inhibit rat aminopeptidase activity ‘in vitro’ in the following order: HTrpNHOH > HPheNHOH ≫ HAIaNHOH. The same hydroxamates markedly enhanced the biological activity of tetragastrin ‘in vivo’. The amplification of the secretory effect, correlated with the amount of the hydroxamate used, strongly suggests that these compounds can stabilize a number of active peptides in vivo by inhibiting their proteolytic degradation.

Characterization and modulation of rat small intestinal brush-border membrane transbilayer fluidity

1991 ◽  
Vol 260 (4) ◽  
pp. G586-G594
Author(s):  
P. K. Dudeja ◽  
R. K. Wali ◽  
J. M. Harig ◽  
T. A. Brasitus
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Leucine Aminopeptidase ◽  
Aminopeptidase Activity ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Leucine Transport ◽  
Small Intestinal

In the present experiments, selective quenching by trinitrophenyl groups as well as steady-state fluorescence polarization and differential polarized phase fluorescence techniques, using three different lipid soluble fluorophores, were used to directly examine the fluidity of the exofacial and cytofacial leaflets of rat small intestinal brush-border membranes. These studies revealed that the fluidity of the exofacial hemileaflet was greater than the cytofacial hemileaflet. Differences in the distribution of phosphatidylcholine and phosphatidylethanolamine, as assessed by phospholipase A2 treatment and trinitrophenylation of aminophospholipids, were, at least partially, responsible for the asymmetrical fluidity of the hemileaflets. Moreover, in vitro addition of benzyl alcohol (final concn 25 mM) preferentially fluidized the exofacial leaflet and concomitantly decreased leucine aminopeptidase activity but did not affect the activities of maltase, sucrase, alkaline phosphatase, or gamma-glutamyltranspeptidase. In vivo addition of the membrane-mobility agent 2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl)octanate] (A2C) (final concn 7.5 microM) preferentially fluidized the cytofacial leaflet and increased Na(+)-gradient-dependent D-glucose transport but not Na(+)-gradient-dependent L-leucine transport.

Anion effects on fluid absorption from rat jejunum perfused in vivo

1983 ◽  
Vol 244 (1) ◽  
pp. G33-G39
Author(s):  
M. H. Humphreys ◽  
L. Y. Chou
Keyword(s):  
Atpase Activity ◽  
Water Absorption ◽  
Brush Border ◽  
Intestinal Transport ◽  
Ringer Solution ◽  
Rat Jejunum ◽  
Perfusion Fluid ◽  
Potent Effect

Perfusion of rat jejunal segments in vivo with an isotonic, HCO3-free SO4-Ringer solution resulted in low rates of net sodium (JNanet) and water absorption. When the perfusion fluid was changed to one containing 25 mM Na2SO3, JNanet increased from 4.7 +/- 1.2 to 11.6 +/- 1.5 (SE) mumol X cm-1 X h-1 (P less than 0.001). This increased absorption was accompanied by comparable increases in chloride and water absorption, occurred without a detectable change in potential difference across the perfused segment, and was readily reversed on reinstitution of perfusion with SO4-Ringer. Perfusion with SO3-Ringer had no effect on electrolyte absorption from terminal segments of rat ileum. Addition of L-phenylalanine stimulated absorption from SO4-Ringer perfusate but not from SO3-Ringer perfusate. Addition of 25 mM NaHCO3 to SO4-Ringer perfusate caused parallel increases in JNanet and JHCO3net; when 25 mM NaHCO3 was added to SO4-Ringer perfusate that also contained 25 mM NaSCN, the same increase in JHCO3net occurred but was not associated with any increase in JNanet. These results indicate a potent effect of SO2-3 and HCO-3 to stimulate JNanet from rat jejunum but not from ileum. These anion effects on intestinal transport in vivo resemble their effects on ATPase activity of brush-border fractions from small intestine in vitro and raise the possibility that these effects on ion transport could be mediated through the changes in brush-border ATPase activity, which are brought about by exposure to these anions, although other explanations are also possible.

Oxytocin analogues with non-coded amino acid residues in position 8: [8-Neopentylglycine]oxytocin and [8-cycloleucine]oxytocin

1987 ◽  
Vol 52 (9) ◽  
pp. 2317-2325 ◽  
Author(s):  
Jan Hlaváček ◽  
Jan Pospíšek ◽  
Jiřina Slaninová ◽  
Walter Y. Chan ◽  
Victor J. Hruby
Keyword(s):  
Amino Acid ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
The Other ◽  
Amino Acid Residues ◽  
Phase Synthesis ◽  
Other Hand ◽  
Fragment Condensation

[8-Neopentylglycine]oxytocin (II) and [8-cycloleucine]oxytocin (III) were prepared by a combination of solid-phase synthesis and fragment condensation. Both analogues exhibited decreased uterotonic potency in vitro, each being about 15-30% that of oxytocin. Analogue II also displayed similarly decreased uterotonic potency in vivo and galactogogic potency. On the other hand, analogue III exhibited almost the same potency as oxytocin in the uterotonic assay in vivo and in the galactogogic assay.

Synthesis of Fragments of the Vasoactive Intestinal Peptide (VIP) and Analysis of Their Residual Biological Activities

1995 ◽  
Vol 60 (7) ◽  
pp. 1229-1235 ◽  
Author(s):  
Ivana Zoulíková ◽  
Ivan Svoboda ◽  
Jiří Velek ◽  
Václav Kašička ◽  
Jiřina Slaninová ◽  
...  
Keyword(s):  
Amino Acid ◽  
Biological Activities ◽  
Residual Activity ◽  
Detailed Examination ◽  
Amino Acid Residues ◽  
Linear Peptide ◽  
Zone Electrophoresis ◽  
Capillary Zone

The vasoactive intestinal (poly)peptide (VIP) is a linear peptide containing 28 amino acid residues, whose primary structure indicates a low metabolic stability. The following VIP fragments, as potential metabolites, and their analogues were prepared by synthesis on a solid: [His(Dnp)1]VIP(1-10), VIP(11-14), [D-Arg12]VIP(11-14), [Lys(Pac)15,21,Arg20]VIP(15-22), and VIP(23-28). After purification, the peptides were characterized by amino acid analysis, mass spectrometry, RP HPLC, and capillary zone electrophoresis. In some tests, detailed examination of the biological activity of the substances in vivo and in vitro gave evidence of a low, residual activity of some fragments, viz. a depressoric activity in vivo for [His(Dnp)1]VIP(1-10) and a stimulating activity for the release of α-amylase in vitro and in vivo for [Lys(Pac)15,21,Arg20]VIP(15-22) and VIP(23-28).

A novel polymorphism of human gene has an amino acid substitution (V365M) that decreases enzymatic activity in vitro and in vivo

2004 ◽  
Vol 76 (6) ◽  
pp. 519-527 ◽  
Author(s):  
T FUKAMI ◽  
M NAKAJIMA ◽  
R YOSHIDA ◽  
Y TSUCHIYA ◽  
Y FUJIKI ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Activity ◽  
Amino Acid Substitution ◽  
Human Gene

Reduced and S-carboxymethylated human growth hormone: a probe for diabetogenic action

1984 ◽  
Vol 247 (5) ◽  
pp. E639-E644
Author(s):  
C. M. Cameron ◽  
J. L. Kostyo ◽  
J. A. Rillema ◽  
S. E. Gennick
Keyword(s):  
Growth Hormone ◽  
Amino Acid ◽  
Human Growth Hormone ◽  
Human Growth ◽  
Mouse Mammary Gland ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Hypophysectomized Rats

The biological activity profile of reduced and S-carboxymethylated human growth hormone (RCM-hGH) was determined to establish its suitability for study of the diabetogenic property of hGH. RCM-hGH was found to have greatly attenuated in vivo growth-promoting activity in the 9-day weight-gain test in hypophysectomized rats (approximately 1%) and to have a similar low order of in vitro activity in stimulating amino acid incorporation into the protein of the isolated rat diaphragm. RCM-hGH also only had approximately 1% of the in vitro insulin-like activity of the native hormone on isolated adipose tissue from hypophysectomized rats. In contrast, RCM-hGH retained substantial in vivo diabetogenic activity in the ob/ob mouse, appearing to have approximately 50% of the activity of the native hormone. RCM-hGH was also found to retain significant, although attenuated (25%), in vitro lactogenic activity when tested for the ability to stimulate amino acid incorporation into a casein-rich protein fraction in mouse mammary gland explants. Because RCM-hGH exhibits a high degree of diabetogenic activity, although lacking significant anabolic or insulin-like activities, it will be useful as a "monovalent" probe for the study of the molecular mechanism of the diabetogenic action of GH.

scholarly journals LASS3 (longevity assurance homologue 3) is a mainly testis-specific (dihydro)ceramide synthase with relatively broad substrate specificity

2006 ◽  
Vol 398 (3) ◽  
pp. 531-538 ◽  
Author(s):  
Yukiko Mizutani ◽  
Akio Kihara ◽  
Yasuyuki Igarashi
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Family Members ◽  
Fatty Acyl ◽  
Ceramide Synthase ◽  
Broad Substrate Specificity ◽  
Acid Protein ◽  
Amino Acid Protein

The LASS (longevity assurance homologue) family members are highly conserved from yeasts to mammals. Five mouse and human LASS family members, namely LASS1, LASS2, LASS4, LASS5 and LASS6, have been identified and characterized. In the present study we cloned two transcriptional variants of hitherto-uncharacterized mouse LASS3 cDNA, which encode a 384-amino-acid protein (LASS3) and a 419-amino-acid protein (LASS3-long). In vivo, [3H]dihydrosphingosine labelling and electrospray-ionization MS revealed that overproduction of either LASS3 isoform results in increases in several ceramide species, with some preference toward those having middle- to long-chain-fatty acyl-CoAs. A similar substrate preference was observed in an in vitro (dihydro)ceramide synthase assay. These results indicate that LASS3 possesses (dihydro)ceramide synthesis activity with relatively broad substrate specificity. We also found that, except for a weak display in skin, LASS3 mRNA expression is limited almost solely to testis, implying that LASS3 plays an important role in this gland.

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