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

1971 ◽  
Vol 41 (5) ◽  
pp. 409-417 ◽  
Author(s):  
R. F. Crampton ◽  
S. D. Gangolli ◽  
Pamela Simson ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
High Capacity ◽  
Protein Digestion ◽  
Amino Acid Residues ◽  
Small Peptides ◽  
Rat Intestine ◽  
Protein Absorption ◽  
Amino Acid Mixtures ◽  
Mucosal Uptake

1. Though the occurrence of intestinal mucosal uptake of intact peptides, with cellular hydrolysis to amino acids, has been established, the importance of this mode of absorption in protein absorption is not known. This paper describes a comparison of the rates of intestinal absorption of pancreatic hydrolysates of four proteins with those of the corresponding acid hydrolysates or amino acid mixtures. 2. The results show that the absorption of pancreatic hydrolysates, consisting largely of small peptides of two to six amino acid residues, is substantially more rapid than that of the corresponding mixtures of free amino acids. This shows that the small intestine has a high capacity for absorption from mixtures of small peptides such as might be produced during protein digestion, and supports the hypothesis that mucosal uptake of intact oligopeptides is an important mode of protein absorption.

Effect of Glycylglycine on Absorption from Human Jejunum of an Amino Acid Mixture Simulating Casein and a Partial Enzymic Hydrolysate of Casein Containing Small Peptides

1977 ◽  
Vol 53 (1) ◽  
pp. 27-33
Author(s):  
P. D. Fairclough ◽  
D. B. A. Silk ◽  
M. L. Clark ◽  
D. M. Matthews ◽  
T. C. Marrs ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Acid Uptake ◽  
Amino Acid Residues ◽  
Small Peptides

1. A jejunal perfusion technique has been used in normal volunteer subjects to study jejunal absorption of amino acid residues from a partial enzymic hydrolysate of casein in which about 50% of the amino acids existed as small peptides, and also from an equivalent mixture of free amino acids. 2. The effect of a high concentration of the dipeptide glycylglycine on the absorption of amino acid residues from these preparations was studied to quantify the importance of mucosal uptake of intact peptides during absorption of the partial hydrolysate of casein. 3. The results were unexpected. Glycylglycine significantly inhibited absorption of several amino acid residues (aspartic acid + asparagine, serine, glutamic acid + glutamine, proline, alanine, phenylalanine, threonine and isoleucine) from the free amino acid mixture, whereas it significantly inhibited the absorption of only two (serine, glutamic acid + glutamine) from the peptide-containing partial casein hydrolysate. 4. The effect of glycylglycine on absorption of amino acids from the mixture of free amino acids was apparently due to inhibition of amino acid uptake by free glycine liberated from the dipeptide during perfusion. The reason for the failure of glycylglycine to cause extensive inhibition of absorption from the partial hydrolysate is not clear. It may be due to glycylglycine being only a weak inhibitor of peptide uptake, but the possibility that some peptides are taken up by a system unavailable to glycylglycine has to be considered.

scholarly journals Effect of co-ingestion of amino acids with rice on glycaemic and insulinaemic response

2015 ◽  
Vol 114 (11) ◽  
pp. 1845-1851 ◽  
Author(s):  
Yean Yean Soong ◽  
Joseph Lim ◽  
Lijuan Sun ◽  
Christiani Jeyakumar Henry
Keyword(s):  
Amino Acids ◽  
Blood Glucose ◽  
Amino Acid ◽  
Glycaemic Index ◽  
Amino Acid Mixture ◽  
Postprandial Blood Glucose ◽  
Acid Mixture ◽  
White Rice ◽  
Amino Acid Mixtures

AbstractConsumption of high glycaemic index (GI) and glycaemic response (GR) food such as white rice has been implicated in the development of type 2 diabetes. Previous studies have reported the ability of individual amino acids to reduce GR of carbohydrate-rich foods. Because of the bitter flavour of amino acids, they have rarely been used to reduce GR. We now report the use of a palatable, preformed amino acid mixture in the form of essence of chicken. In all, sixteen healthy male Chinese were served 68 or 136 ml amino acid mixture together with rice, or 15 or 30 min before consumption of white rice. Postprandial blood glucose and plasma insulin concentrations were measured at fasting and every 15 min after consumption of the meal until 60 min after the consumption of the white rice. Subsequent blood samples were taken at 30-min intervals until 210 min. The co-ingestion of 68 ml of amino acid mixture with white rice produced the best results in reducing the peak blood glucose and GR of white rice without increasing the insulinaemic response. It is postulated that amino acid mixtures prime β-cell insulin secretion and peripheral tissue uptake of glucose. The use of ready-to-drink amino acid mixtures may be a useful strategy for lowering the high-GI rice diets consumed in Asia.

The C-terminal sequence of amino acid residues of κ-casein isolated from buffalo's milk

1967 ◽  
Vol 34 (1) ◽  
pp. 85-88 ◽  
Author(s):  
M. H. Abd El-Salam ◽  
W. Manson
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Peptide Chain ◽  
Amino Acid Residues ◽  
Terminal Sequence ◽  
Carboxypeptidase A ◽  
Phosphorous Content ◽  
Single Peptide

SummaryWhen κ-casein from buffalo's milk was treated with carboxypeptidase A (EC 3. 4. 2. 1),4 amino acids, valine, threonine, serine and alanine were released from the protein in a manner consistent with the view that they originate in the C-terminal sequence of a single peptide chain. The amounts produced suggest a minimum molecular weight for buffalo κ-casein of approximately 17000, in agreement with the value calculated from the phosphorous content on the basis of the presence of 2 phosphorus atoms/molecule. A comparison is made with the C-terminal sequence reported for bovine κ-casein.

Structural characterization of folded and extended conformations in peptides containing γ amino acids with proteinogenic side chains: crystal structures of γn, (αγ)n and γγδγ sequences

2015 ◽  
Vol 39 (5) ◽  
pp. 3319-3326 ◽  
Author(s):  
Madhusudana M. B. Reddy ◽  
K. Basuroy ◽  
S. Chandrappa ◽  
B. Dinesh ◽  
B. Vasantha ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Crystal Structures ◽  
Structural Characterization ◽  
Side Chains ◽  
Amino Acid Residues

γn amino acid residues can be incorporated into structures in γn and hybrid sequences containing folded and extended α and δ residues.

scholarly journals SLC6A14, a Pivotal Actor on Cancer Stage: When Function Meets Structure

2019 ◽  
Vol 24 (9) ◽  
pp. 928-938 ◽  
Author(s):  
Luca Palazzolo ◽  
Chiara Paravicini ◽  
Tommaso Laurenzi ◽  
Sara Adobati ◽  
Simona Saporiti ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Amino Acid ◽  
Molecular Dynamics Simulations ◽  
Electrostatic Interactions ◽  
Amino Acid Residues ◽  
Dibasic Amino Acid ◽  
Novel Target ◽  
Function Relationship ◽  
Dynamics Simulations

SLC6A14 (ATB0,+) is a sodium- and chloride-dependent neutral and dibasic amino acid transporter that regulates the distribution of amino acids across cell membranes. The transporter is overexpressed in many human cancers characterized by an increased demand for amino acids; as such, it was recently acknowledged as a novel target for cancer therapy. The knowledge on the molecular mechanism of SLC6A14 transport is still limited, but some elegant studies on related transporters report the involvement of the 12 transmembrane α-helices in the transport mechanism, and describe structural rearrangements mediated by electrostatic interactions with some pivotal gating residues. In the present work, we constructed a SLC6A14 model in outward-facing conformation via homology modeling and used molecular dynamics simulations to predict amino acid residues critical for substrate recognition and translocation. We docked the proteinogenic amino acids and other known substrates in the SLC6A14 binding site to study both gating regions and the exposed residues involved in transport. Interestingly, some of these residues correspond to those previously identified in other LeuT-fold transporters; however, we could also identify a novel relevant residue with such function. For the first time, by combined approaches of molecular docking and molecular dynamics simulations, we highlight the potential role of these residues in neutral amino acid transport. This novel information unravels new aspects of the human SLC6A14 structure–function relationship and may have important outcomes for cancer treatment through the design of novel inhibitors of SLC6A14-mediated transport.

scholarly journals Hyaluronan-binding region of aggrecan from pig laryngeal cartilage. Amino acid sequence, analysis of N-linked oligosaccharides and location of the keratan sulphate

1992 ◽  
Vol 286 (3) ◽  
pp. 761-769 ◽  
Author(s):  
F P Barry ◽  
J U Gaw ◽  
C N Young ◽  
P J Neame
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Signal Peptidase ◽  
Amino Acid Residues ◽  
Terminal Sequence ◽  
Binding Region ◽  
Keratan Sulphate ◽  
Laryngeal Cartilage ◽  
Hyaluronan Binding

The hyaluronan-binding region (HABR) was prepared from pig laryngeal cartilage aggrecan and the amino acid sequence was determined. The HABR had two N-termini: one N-terminal sequence was Val-Glu-Val-Ser-Glu-Pro (367 amino acids in total), and a second N-terminal sequence (Ala-Ile-Ser-Val-Glu-Val; 370 amino acids in total) was found to arise due to alternate cleavage by the signal peptidase. The N-linked oligosaccharides were analysed by examining their reactivity with a series of lectins. It was found that the N-linked oligosaccharide on loop A was of the mannose type, while that on loop B was of the complex type. No reactivity was detected between the N-linked oligosaccharide on loop B' and any of the lectins. The location of keratan sulphate (KS) in the HABR was determined by Edman degradation of the immobilized KS-containing peptide. The released amino acid derivatives were collected and tested for the presence of epitope to antibody 5-D-4. On the basis of 5-D-4 reactivity and sequencing yields, the KS chains are attached to threonine residues 352 and 357. There is no KS at threonine-355. This site is not in fact in G1, but about 16 amino acid residues into the interglobular domain. Comparison of the structure of the KS chain from the HABR and from the KS domain of pig laryngeal cartilage aggrecan was made by separation on polyacrylamide gels of the oligosaccharides arising from digestion with keratanase. Comparison of the oligosaccharide maps suggests that the KS chains from both parts of the aggrecan molecule have the same structure.

ChemInform Abstract: β-Nitro-α-amino Acids as Latent α,β-Dehydro-α-amino Acid Residues in Peptides.

ChemInform ◽  
2010 ◽  
Vol 30 (34) ◽  
pp. no-no
Author(s):  
Phillip A. Coghlan ◽  
Christopher J. Easton
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Residues

Renal Tubular Transport of Amino Acids

1971 ◽  
Vol 17 (4) ◽  
pp. 245-266 ◽  
Author(s):  
John Atherton Young ◽  
Benedict Sol Freedman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Proximal Tubule ◽  
Amino Nitrogen ◽  
High Capacity ◽  
High Specificity ◽  
Brush Borders ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Abstract Cushny in 1917 first remarked on the extensive amino acid reabsorption which occurs in the nephron. Although many workers since then have studied the nature and localization of the reabsorptive mechanism, progress has been slow because of the technical difficulties of micropuncture work. The bulk of filtered amino nitrogen is reabsorbed in the proximal tubule although the possibility of there being more distal reabsorptive (or secretory) sites cannot be excluded. It is also uncertain whether all segments of the proximal tubule contribute equally to the reabsorptive process. Amino acid reabsorption is an active process involving numerous illdefined steps, the first of which is binding to the brush borders. Renal amino acid transport mechanisms are of two kinds: the high-capacity low-specificity systems transport whole groups of amino acids—the acidic, basic, neutral, and imino-glycine groups—while the other, the low-capacity high-specificity systems, transport single or perhaps pairs of amino acids only.

INHIBITION OF GROWTH OF PSEUDOMONAS DENITRIFICANS BY AMINO ACIDS

1966 ◽  
Vol 12 (6) ◽  
pp. 1095-1098 ◽  
Author(s):  
Horace J. Daniels
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Basal Medium ◽  
Ammonium Phosphate ◽  
Complete Medium ◽  
Mineral Salts ◽  
Culture Studies ◽  
Pseudomonas Denitrificans ◽  
Inhibition Of Growth ◽  
Amino Acid Mixtures

A large number of amino acids failed to support growth of Pseudomonas denitrificans in a basal medium composed of glucose, ammonium phosphate, and other mineral salts. Inability of an amino acid to support growth correlated well with its inhibitory action in a complete medium made up by adding L-glutamic acid to the basal medium. D-Amino acids were more toxic than the corresponding L-forms, and neutral amino acids were more toxic than acidic amino acids. Basic amino acids which were least toxic supported the best growth. The danger of the indiscriminate use of amino acid mixtures for culture studies is discussed.

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