Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “dipeptides”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources
PubMed1990

Enhancement of tumour necrosis factor production and sensitivity to interleukin-2 of human peripheral blood mononuclear cells stimulated by lipopolysaccharide and muramyl dipeptide in vitro.

The effect of lipopolysaccharide, muramyl dipeptide, and a combination of these agents in vitro on the production of tumour necrosis factor (TNF) by human peripheral blood mononuclear cells (PBMC; monocytes and lymphocytes) and on the sensitivity of these cells to recombinant interleukin-2 (IL-2) was studied. Both lipopolysaccharide and muramyl dipeptide, alone and combined, induced the production of TNF alpha by blood monocytes and lymphocytes, although the T-cells made only a very small contribution to the TNF produced by the lymphocyte fraction, most being produced by the B-cells. The B-lymphocytes and monocytes also spontaneously produced TNF alpha. Pretreatment of the mononuclear cells with a combination of lipopolysaccharide and muramyl dipeptide, but not with each preparation separately, led to enhancement of the proliferative response of these cells to recombinant IL-2. Incubation of mononuclear cells with muramyl dipeptide, muramyl dipeptide plus lipopolysaccharide, and to a lesser extent with lipopolysaccharide alone led to the generation of more-active lymphokine-activated killer cells in the presence of IL-2 than when IL-2 was used alone. The resultant lymphokine-activated killer cells lysed both human and murine tumour target cells.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1999

Chiral electrokinetic chromatography using dipeptide polymeric surfactants: present state of the art.

Polymeric amino acid based surfactants have been recently employed as pseudostationary phases in capillary electrophoresis. These phases are effective for chiral separation of analytes in different charge states and hydrophobicities. This review paper focuses on polymeric dipeptide surfactants. The benefits of dipeptide over single amino acid micelle polymers are shown. Some aspects of dipeptide surfactants that are presented here includes the amino acid order, effect of number and position of chiral centers, and steric factors on enantiomeric separation of chiral compounds in different charge states. In addition, the preferential site of interaction of the chiral analyte using diastereomers of polymeric dipeptide surfactants is discussed.

Amino Acids↗
PubMed2000

Chiral separation with dipeptide-terminated polymeric surfactants: the effect of an extra heteroatom on the polar head group.

Chiral recognition of two binaphthyl derivatives and three benzodiazepines were studied by use of polymeric surfactants in electrokinetic chromatography. Four specific dipeptide terminated (multichiral) micelle polymers were synthesized for this study. These include poly (sodium-N-undecanoyl-L-alanyl-leucinate)-(poly L-SUAL), poly (sodium-N-undecanoyl-L-valyl-leucinate) (poly L-SUVL), poly (sodium-N-undecanoyl-Lseryl-leucinate) (poly L-SUSL), and poly(sodium-N-undecanoyl-L-threonyl-leucinate) (poly L-SUTL). In addition to the chiral separation study, the physicochemical properties (critical micelle concentration and specific rotation) of each polymer were investigated. The molecular weights of the various dipeptide-terminated micelle polymers were determined using analytical ultracentrifugation. These dipeptide-terminated micelle polymers were designed to study the effect of the extra heteroatom at the polar head group of the micelle polymer (i.e., poly L-SUSL compared to poly L-SUAL and poly L-SUTL compared to poly L-SUVL) on the enantiomeric separation of the binaphthyl derivatives and benzodiazepines. The synergistic effect of three chiral centers (poly L-SUTL) provided improved resolution over that of two chiral centered dipeptide-terminated micelle polymer in the case of (+/-)-temazepam, (+/-)-oxazepam, (+/-)-binaphthol, and (+/-)-binaphthol phosphate. The chiral recognition mechanisms in these cases were additionally controlled by the presence of the extra heteroatom located on the polar head group of the micelle polymers.

Anti-Anxiety Agents↗
PubMed1977

Clearance of dipeptides from plasma: role of kidney and intestine.

The metabolic fate of glycylglycine and glycyl-L-leucine administered intravenously to rats, and the processes involved in the clearance of these dipeptides from plasma, have been studied. The dipeptides disappeared rapidly from plasma without being lost in the urine or accumulating in body tissues, but concentrations of glycine or leucine, or both, increased markedly in plasma and body tissues. All tissues except blood had considerable hydrolase activity against Gly-Gly and Gly-Leu, with kidney and intestine being far more active than liver and muscle in this regard. When uptake of glycylsarcosine, which is resistant to hydrolysis, was investigated after intravenous injection, its disappearance from plasma was slower than that of Gly-Gly, but Gly-Sar accumulated in all tissues examined (liver, muscle, renal cortex and intestinal mucosa). Its concentration in the renal cortex far exceeded (over 14-fold) that in other tissues, and a considerable portion of the injected Gly-Sar dose appeared in the urine. Bilateral nephrectomy did not have a remarkable effect on the plasma half-life of Gly-Leu or Gly-Gly but markedly prolonged that of Gly-Sar. Nephrectomy also allowed greater tissue accumulation of Gly-Sar and recovery of Gly-Gly and Gly-Leu from tissues. The plasma half-life of Gly-Gly was also not remarkably affected by total enterectomy. These studies suggest that (a) clearance of dipeptides from plasma is chiefly a function of tissue uptake and hydrolysis, and (b) among dipeptides, those resistant to hydrolysis depend to a great extent on kidneys for their clearance from plasma.

Amino Acids↗
PubMed2001

Chiral recognition of dipeptide methyl esters by an anionic beta-cyclodextrin.

Chiral recognition of dipeptide methyl esters by anionic heptakis[6-carboxymethylthio-6-deoxy]-beta-cyclodextrin (per-CO(2)(-)-beta-CD) was studied in D(2)O at pD 7.0 by means of (1)H NMR spectroscopy. The methyl esters of alanylalanine (Ala-Ala-OMe), alanylleucine (Ala-Leu-OMe), alanyltryptophan (Ala-Trp-OMe), glycyltryptophan (Gly-Trp-OMe), valyltryptophan (Val-Trp-OMe), leucyltryptophan (Leu-Trp-OMe), and tryptophylalanine (Trp-Ala-OMe) were used as the dipeptides. The binding constant (K) determined from NMR titration increases in the order Ala-Ala-OMe < Ala-Leu-OMe < Ala-Trp-OMe, suggesting that van der Waals interactions between the host and the guest participate in complexation. Coulomb interactions between the protonated dipeptide methyl esters and the anionic host seem to be another attractive force. Per-CO(2)(-)-beta-CD interacts with the (R,R)-enantiomers of the dipeptide methyl esters more strongly than the (S,S)-enantiomers. Such enantioselectivity corresponds to that for alpha-amino acid methyl esters such as Leu-OMe and Trp-OMe, whose (R)-enantiomers are the preferable guests. The enantioselectivity is mainly dominated by amino acid residue at the C-terminal and chirality at the N-terminal residue plays an assistant role. An asymmetrically twisted shape of the host cavity may be essential for chiral recognition.

Anions↗
PubMed2004

Characterization of alpha- and gamma-glutamyl dipeptides by negative ion collision-induced dissociation.

The low-energy CID mass spectra of the [M-H](-) ions of a variety of dipeptides containing glutamic acid have been obtained using cone-voltage collisional activation. Dipeptides with the gamma-linkage, H-Glu(Xxx-OH)-OH, are readily distinguished from those with the alpha-linkage, H-Glu-Xxx-OH, by the much more prominent elimination of H-Xxx-OH from the [M-H](-) ions of the former isomers, resulting in formation of m/z 128, presumably deprotonated pyroglutamic acid. Dipeptides with the reverse linkage, H-Xxx-Glu-OH, show distinctive fragmentation reactions of the [M-H](-) ions including enhanced elimination of CO(2) and formation of deprotonated glutamic acid. Exchange of the labile hydrogens for deuterium has shown that there is considerable interchange of C-bonded hydrogens with labile (N- and O-bonded) hydrogens prior to most fragmentation reactions. All dipeptides show loss of H(2)O from [M-H](-). MS(3) studies show that the [M-H-H(2)O](-) ion derived from H-Glu-Gly-OH has the structure of deprotonated pyroglutamylglycine while the [M-H-H(2)O](-) ions derived from H-Glu(Gly-OH)-OH and H-Gly-Glu-OH show a different fragmentation behaviour indicating distinct structures for the fragment ions.

Dipeptides↗
PubMed2006

Glycation of lysine-containing dipeptides.

Protein glycation through Maillard reaction (MR) is a fundamental reaction both in foods and in the human body. The first step of the reaction is the formation of Amadori product (AP) that is converted into intermediate and advanced MR products during reaction development. Although the MR is not an enzymatic reaction, a certain degree of specificity in the glycation site has been observed. In the present study, we have monitored the glycation of different lysine-containing dipeptides to evaluate the influence on the NH(2) reactivity of the neighboring amino acid.Lysine dipeptides were reacted with glucose, galactose, lactose and maltose. The formation and identification of glycated compounds were monitored by mass spectrometry (MALDI-TOF and ESI-MS/MS) and by HPLC of their Fmoc derivatives. MS/MS analysis showed that the glucose APs formed on dipeptides have a characteristic fragmentation pattern: the fragment at [M - 84](+) due to the formation of pyrylium and furylium ion is mainly present in the monoglucosylated form, while the [M - 162](+) and the [M - 324](+) are more evident in the fragmentation pattern of the diglucosylated forms. The nature of the vicinal amino acids strongly affects lysine reactivity towards the different carbohydrates: the presence of hydrophobic residues such as Ile, Leu, Phe strongly increases lysine reactivity. Contrasting results were obtained with basic residues. The Lys-Arg dipeptide was among the most reactive while the Lys-Lys was not.

Dipeptides↗
PubMed2002

L-delta-(alpha-Aminoadipoyl)-L-cysteine-D-valine synthetase: production of dipeptides containing valine residue at its C-terminus.

L-delta-(alpha-Aminoadipoyl)-L-cysteine-D-valine synthetase (ACVS) has been recently studied as a model enzyme for peptide synthetases. It was found that in the absence of alpha-aminoadipic acid but in the presence of several cysteine analogues it was incorporated into several analogue dipeptides upon incubation of the potential cysteine analogues with ACVS. [(14)C]Cysteine was incorporated into the[(14)C]cysteinyl-valine analogue dipeptides. Notably, [(14)C]valine incorporation in the presence of N-acylated cysteine analogues was observed. The alpha-aminoadipic acid activation site is influential, inhibitory or promotive, on the production of these putative dipeptide products. The production of dipeptide analogues, containing valine or analogues at the C-terminus, leads to the speculation that the biosynthetic direction of ACV could be from the C-terminus to the N-terminus.

2-Aminoadipic Acid↗
PubMed1975

Structure-taste relationship of some sweet-tasting dipeptide esters.

The sweetness of dipeptide esters, structurally related to L-aspartyl-L-phenylalanine methyl ester (Aspartame), depends among other things on molecular size. This paper describes a method for predicting whether a dipeptide ester is sweet or not with the aid of atomic models. The method is based on the determination of the size, length and shape of the side chain (R) of the amino-acid ester attached to L-aspartic acid. We measured the side chains of 28 dipeptide esters, 13 of which were synthesized and evaluated for sweetness in our laboratory. Data of the other esters were taken from the literature. Twentyone dipeptide esters were sweet; the size and length of the side chains could be correlated with the degree of sweetness. An ester is sweet provided the length of the side chain (R) is between 4.8 and 8.8 A, and its size greater than or equal to 29 A; as for shape of R in sweet esters, there were two maxima in space filling at about 2 and 4 A or about 3 and 5 A from the asymmetric carbon atom.

Aspartame↗
PubMed1996

Effect of a dipeptide inhibiting ubiquitin-mediated protein degradation nerve-dependent limb regeneration in the newt.

The dipeptide Leu-Ala, which inhibits ubiquitin-mediated protein degradation, has been shown to act in vitro as an inhibitor of neurite outgrowth of PC12 cells (Hondermarck et al. [1992] Biochem. Biophys. Res. Commun. 189:280). Using agarose beads as vehicles, we tested, in vivo, the effect of this dipeptide (and the inactive inverse, Ala-Leu, as a control) on limb regeneration in the newt (Triturus cristatus), a nerve-dependent developmental process. Leu-Ala inhibited the growth of mid-bud blastemas without altering blastema differentiation, while Ala-Leu had no effect. Cytological observations of dipeptide-treated blastemas using Bodian staining or neurofilament antibodies showed that all the blastema tissues were unmodified except with regard to innervation. Leu-Ala-treated blastemas were devoid of nerve fibers in the epidermal cap, while the mesenchyme distal to the dipeptide impregnated bead exhibited fewer nerve fibers than did Ala-Leu-treated blastemas, which were similar to the control nontreated blastemas. Thus, Leu-Ala, in reducing blastema innervation, inhibits its growth in the same manner as surgical denervation.

Animals↗
PubMed1988

Influence of two glutamine-containing dipeptides on growth of mammalian cells.

The instability of the amino acid glutamine prompted us to investigate substitute compounds appropriate for culture conditions. The effect of two glutamine-containing dipeptides, alanylglutamine (Ala-Gln) and glycylglutamine (Gly-Gln), on the growth behavior of a hematopoietic cell line in culture (K562) was investigated. Growth rates and [3H]thymidine incorporation rates of cells cultivated in sterile-filtrated media, containing glutamine (Gln) or Ala-Gln or Gly-Gln, were not statistically different. Although heart-sterilization of media containing Gln caused approximately 95% decomposition of the Gln, both dipeptides remained unaltered. Consequently, cell growth was drastically decreased when autoclaved free Gln-containing media were used, but growth was unaffected in the presence of autoclaved dipeptides. Both Ala-Gln and Gly-Gln have an advantage over free Gln as growth factors for cell culture due to the stability of the dipeptides during both autoclaving and storage; the biological activity, however, is comparable.

Cell Division↗
PubMed2002

Copper(II)- cis, cis-1,3,5-triaminocyclohexane complex-promoted hydrolysis of dipeptides: kinetic, speciation and structural studies.

The hydrolysis of glycylglycine (GylGly), glycyl-L-leucine (GlyLeu), L-leucylglycine (LeuGly) and glycyl-DL-serine (GlySer) promoted by a copper(II)- cis, cis-1,3,5-triaminocyclohexane complex [Cu(II)TACH] was investigated at 70 degrees C and pH 7-10, using HPLC. The observed pseudo-first-order rate constants (k(obs)) and rate enhancing factors (REF) were as follows: 4.1x10(-3 )h(-1)(REF=23) for GylGly, 1.6x10(-3 )h(-1)(REF=21) for GlyLeu, 5.1x10(-3 )h(-1)(REF=64) for LeuGly and 9.2x10(-2 )h(-1)(REF=47) for GlySer [pH 8.1, dipeptide 2 mM, copper(II) 2 mM and TACH 2 mM]. Based on the pH dependence and dipeptide concentration dependence of the initial rates and speciation of the Cu(II)-TACH-dipeptide system at 25 degrees C and I=0.1, the reactions proceed via the formation of a ternary complex [Cu(TACH)(dipeptide)](+) as an intermediate followed by OH(-)-dependent and OH(-)-independent paths to give amino acid(s). GylGly, GlyLeu and LeuGly preferred the OH(-)-dependent path, while GlySer preferred the OH(-)-independent path. The latter can be explained by the intramolecular attack of the amide carbonyl group coordinated with its oxygen atom by the OH group in the serine residue. The X-ray crystal structure of [Cu(TACH)(GlyGly)]BPh(4).MeOH confirmed that GlyGly coordinates to copper(II) ion with its terminal amino N and amide O atoms. The crystal structures of [Cu(TACH)(Gly)]BPh(4) and [Cu(2)(TACH)(2)(OH)(2)](ClO(4))(2).NaClO(4).H(2)O are also reported.

Chromatography, High Pressure Liquid↗
PubMed1975

Dipeptide transport in isolated intestinal brush border membrane.

Transport of glycyl-L-leucine into isolated brush border membrane vesicles was studied. On the basis of the following observations it was postulated that glycyl-L-leucine was transported intact by a specific dipeptide mechanism. (1) The differing time course and Na-+ stimulation of glycine, L-leucine and glycyl-L-leucine. (2) The failure of glycine and L-leucine to inhibit glycyl-L-leucine transport. (3) Initial presence of dipeptide within the vesicle. (4) Inhibition of glycyl-L-leucine uptake by other dipeptides. (5) The occurrence of accelerated amino acid uptake in the presence of the dipeptide.

Animals↗
PubMed1981

Evidence for a dipeptide transport system in renal brush border membranes from rabbit.

Papain treatment of renal brush border vesicles was carried out as a successful first step towards the purification of the membrane components involved in dipeptide transport. The treated vesicles exhibited increased specific transport activity of glycyl-L-proline. In contrast, the specific transport activity of L-alanine in the treated vesicles was less than that in the control vesicles. Papain treatment resulted in the solubilization of 38% of protein, 55% of alkaline phosphatase, 90% of gamma-glutamyltransferase and 95% of leucine aminopeptidase. There was no change in the intravesicular volume nor was there any increase in vesicular permeability. Glycyl-L-proline transport was Na+-independent in the control and papain-treated vesicles. Diamide reduced the Na+-dependent L-alanine transport while glycyl-L-proline transport remained unaffected in the presence of Na+. Many dipeptides inhibited glycyl-L-proline transport both in the presence and absence of Na+. The inhibition by dipeptides was greater than the inhibition by equivalent concentrations of free amino acids. These data demonstrate that renal brush border vesicles can efficiently handle dipeptides by a mechanism completely different from that of amino acid transport.

Alanine↗
PubMed1984

Carrier-mediated transport of cephalexin via the dipeptide transport system in rat renal brush-border membrane vesicles.

Carrier-mediated transport of aminocephalosporin antibiotics by renal brush-border membrane vesicles has been studied in relation to the transport systems for dipeptides and amino acids. Dipeptides such as L-carnosine (beta-alanyl-L-histidine) and L-phenylalanylglycine competitively inhibited the uptake of cephalexin, but amino acids did not. Cephalexin uptake was stimulated by the countertransport effect of L-carnosine in the normal and papain-treated vesicles, and by the effect of L-phenylalanylglycine only in the papain-treated vesicles. In the papain-treated vesicles, the hydrolysis of dipeptides was markedly decreased, and the specific activity for cephalexin transport was increased approx. 2-fold because of the partial removal of membrane proteins. These results suggest that carrier-mediated transport of cephalexin can be transported by the system for dipeptides in renal brush-border membranes.

Amino Acids↗
PubMed1992

Cefaclor uptake by the proton-dependent dipeptide transport carrier of human intestinal Caco-2 cells and comparison to cephalexin uptake.

The human Caco-2 cell line spontaneously differentiates in culture to epithelial cells possessing intestinal enterocytic-like properties. These cells possess a proton-dependent dipeptide transport carrier that mediates the uptake of the cephalosporin antibiotic cephalexin (Dantzig, A.H. and Bergin, L. (1990) Biochim. Biophys. Acta 1027, 211-217). In the present study, the uptake of cefaclor was examined and found to be sodium-independent, proton-dependent, and energy-dependent. The initial rate of D-[3-phenyl-3H]cefaclor uptake was measured over a wide concentration range; uptake was mediated by a single saturable transport carrier with a Km of 7.6 mM and a Vmax of 7.6 nmol/min per mg protein and by a non-saturable component. Uptake was inhibited by dipeptides but not amino acids. The carrier showed a preference for the L-isomer. The effect of the presence of a 5-fold excess of other beta-lactam antibiotics was examined on the initial rates of 1 mM cefaclor and 1 mM cephalexin uptake. Uptake rates were inhibited by the orally absorbed antibiotics, cefadroxil, cefaclor, loracarbef, and cephradine and less so by the parenteral agents tested. The initial uptake rates of both D-[9-14C]cephalexin and D-[3-phenyl-3H]cefaclor were competitively inhibited by cephalexin, cefaclor, and loracarbef with Ki values of 9.2-13.2, 10.7-6.2, and 7.7-6.4 mM, respectively. Taken together, these data suggest that a single proton-dependent dipeptide transport carrier mediates the uptake of these orally absorbed antibiotics into Caco-2 cells, and provide further support for the use of Caco-2 cells as a cellular model for the study of the intestinal proton-dependent dipeptide transporter.

2,4-Dinitrophenol↗
PubMed1988

Further evidence for the presence of a thiazoline ring in the isoleucylcysteine dipeptide intermediate in bacitracin biosynthesis.

Isoleucylcysteine dipeptide, a first intermediate peptide in bacitracin biosynthesis, was liberated from the enzyme protein and oxidized with manganese dioxide in dimethylsulfoxide. The resulting oxidation product was identified by thin-layer chromatography as 2-(2-methyl-l-oxobutyl)-thiazole-4-carboxylic acid which has been isolated from the hydrolysate of bacitracin F. This result shows that the intermediate dipeptide contains a thiazoline ring, and that the thiazoline ring is synthesized at the dipeptide stage in the process of peptide chain elongation in bacitracin biosynthesis. Improbability of non-enzymatic dehydrative cyclization of the dipeptide is discussed.

Bacitracin↗
PubMed1987

Binding of the Ile-Val and Val-Val effector dipeptides to the binary adducts of bovine trypsinogen with Kunitz and Kazal inhibitors as well as the acylating agent p-nitrophenyl p-guanidinobenzoate. A thermodynamic and kinetic study.

Thermodynamics and kinetics of binding of the Ile-Val and Val-Val effector dipeptides to the binary adducts of bovine trypsinogen with the bovine basic pancreatic trypsin inhibitor (BPTI, Kunitz inhibitor), the porcine pancreatic secretory inhibitor (PSTI, Kazal inhibitor) and the acylating agent p-nitrophenyl p-guanidinobenzoate have been investigated at pH 7.4 and 21(+/- 0.5) degrees C. The affinity of both effector dipeptides for bovine trypsinogen: BPTI and bovine trypsinogen: PSTI binary adducts is higher than that observed for the formation of the dipeptide: bovine trypsinogen: p-guanidinobenzoate ternary complexes; moreover, the affinity of Ile-Val for the zymogen binary adducts is higher than that observed for Val-Val association. Binding of Ile-Val and Val-Val to the bovine trypsinogen binary complexes conforms to the induced-fit model, which consists of a fast pre-equilibrium followed by intramolecular isomerization change(s), the latter fast pre-equilibrium followed by intramolecular isomerization change(s), the latter representing the rate-limiting first-order process. For the three bovine trypsinogen systems considered, the rate of the intramolecular isomerization change(s) is essentially independent of the nature of the dipeptide and of the proenzyme binary complex.

Animals↗