1,720,964 research outputs found
Effects of peptide T derivatives on the proliferation of cultured human keratinocytes.
No full text[D-Ala1]peptideT-amide, the linear hexapeptide H-Thr-Hse-Asn-Tyr-Thr-Asp-OH (LPT) and its cyclic analog, cyclo(-Thr-Hse-Asn-Tyr-Thr-Asp-) (CPT), were tested for their effects on the proliferation of cultured normal human keratinocytes (KTs) in comparison with vasoactive intestinal peptide (VIP). [D-Ala1]PT-NH2, LPT and VIP (all 0.1 mumol/l) increased the cell number in KT cultures, whereas CPT was ineffective. The VIP antagonist [N-Ac-Tyr1,D-Phe2]GRF (1-29)-NH2 significantly inhibited the VIP effects on KTs. On the other hand this antagonist did not affect the peptide T (PT) compounds-induced stimulation of KTs, providing indirect evidence that the mitogenic effects of VIP and PT peptides are probably mediated via different receptors
Studies on the anti-phospholipase A2 and anti-inflammatory activities of a uteroglobin fragment and related peptides
No full textThe nonapeptide antiflammin P1 (H-Met-Gln-Met-Lys-Lys-Val-Leu-Asp-Ser-OH), its isoAsp8 analogue and the corresponding aminosuccinyl peptide were prepared, characterized and tested for inhibition of phospholipase A2 (PLA2) in vitro and for anti-inflammatory activity in vivo under assay conditions recently recommended. All peptides are devoid of PLA2 inhibitory and anti-inflammatory activity
Synthesis and Opioid Activity of tyrosine sulfate containing dermorphin and Deltorphin Peptides
No full textTo study the effect of the sulfate ester moiety on the opioid activity, we prepared two tyrosine sulfate-(Tyr(SO3H)-containing dermorphin and deltorphin peptides. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membranes and in two bioassays, using guinea pig ileum and mouse vas deferens. In comparison to original peptides and morphine, the obtained data indicate that whereas H-Tyr(SO3H)-D-Ala-Phe-Gly-NH2 shows very minimal interaction with opioid receptors, H-Tyr(SO3H)-D-Ala-Phe-Asp-Val-Val-Gly-NH2 retains a significant activity
Structure–activity relationships of cyclic and linear peptide T analogues
No full textUsing the potent cyclic peptide T analog [formula: see text] as parent compound, a series of analogues were synthesized and their potencies in a monocyte chemotaxis assay were compared with those of correspondingly modified linear peptides. Structure-activity relationships observed with cyclic compounds did not always parallel those determined with linear analogues. [formula: see text] showed the highest affinity to CD4 receptor of monocytes of any peptide thus far studied. It also proved to be highly resistant to degradation by plasma or brain enzymes
Synthesis and opioid activity of tyrosine sulfate containing dermorphin and deltorphin peptides
No full textTo study the effect of the sulfate ester moiety on the opioid activity, we prepared two tyrosine sulfate-(Tyr(SO3H)-containing dermorphin and deltorphin peptides. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membranes and in two bioassays, using guinea pig ileum and mouse vas deferens. In comparison to original peptides and morphine, the obtained data indicate that whereas H-Tyr(SO3H)-D-Ala-Phe-Gly-NH2 shows very minimal interaction with opioid receptors, H-Tyr(SO3H)-D-Ala-Phe-Asp-Val-Val-Gly-NH2 retains a significant activity
Structure-activity ralationships of cyclic and linear peptide T analogues
No full textUsing the potent cyclic peptide T analog [formula: see text] as parent compound, a series of analogues were synthesized and their potencies in a monocyte chemotaxis assay were compared with those of correspondingly modified linear peptides. Structure-activity relationships observed with cyclic compounds did not always parallel those determined with linear analogues. [formula: see text] showed the highest affinity to CD4 receptor of monocytes of any peptide thus far studied. It also proved to be highly resistant to degradation by plasma or brain enzymes
Synthesis and antiaggregatory activity of antiflammin related peptides
No full textThe peptide H-Lys-Val-Leu-Asp-OH (KVLD), derived from antiflammins, and its analog H-Lys-Val-Asp-Leu-OH (KVDL) were prepared by solution synthesis. KVLD does not inhibit platelet aggregation in contrast to the results recently published
Synthesis and activity of new linear and cyclic peptide T derivatives
No full textLinear and head to tail cyclic hexapeptide analogs (Xaa-Thr-Thr-Asn-Tyr-Thr, Xaa = D-Asp or D-iso-Asp) of peptide T were prepared and tested for human monocyte chemotaxis. All new compounds showed significant bioactivity. In particular, the conformational restriction introduced into cyclo(-D-iso-Asp-Thr-Thr-Asn-Tyr-Thr-) was very suitable for CD4 receptor binding. The cyclic peptides also proved to be highly resistant to degradation by plasma or brain enzymes
Phe3-substituted analogues of deltorphin C. Spatial conformation and topography of the aromatic ring in peptide recognition by delta opioid receptors
No full textIn order to study the contribution of the electronic, hydrophobic, and conformational properties of the amino acid residue at position 3 in deltorphin C on binding to delta and mu opioid receptors, a series of 5- and 6-membered ring and bicyclic amino acid replacements at position 3 were prepared by solution synthesis methods. In general, the substitutions were deleterious for high delta affinity (Ki delta) and delta selectivity (Ki mu/Ki delta). However, several notable exceptions were recognized: peptides containing the constrained, bicyclic structures Aic3 and (R or S) Atc3 enhanced delta affinity, but only the latter increased delta selectivity 4-fold (= 2475) relative to deltorphin C (= 661); at the other extreme, delta affinity of N alpha MePh3 fell 900-fold. Bioassays of [N alpha MePhe3]-, [(R or S)C alpha MePhe3]-, [Tic3]-, [Aic3]-, and [(R or S) Atc3]deltorphin C using guinea pig ileum (GPI) and mouse vas deferens (MVD) for mu and delta bioactivity, respectively, revealed a significant correlation (r = 0.916) between MVD bioactivity and delta binding in brain membranes. [(R or S)Atc3]deltorphin C also exhibited the highest biological selectivity (GPI/MVD) (= 3,522), which was 3-fold greater than that observed for deltorphin C. Molecular modelling of [N alpha MePhe3]- and [(S)Atc3]deltorphin C established that these amino acid replacements for Phe3 produce alterations in the backbone (phi,psi) and side-chain (chi 1,chi 2) dihedrals which critically affect the flexibility of the peptide and possibly limit accessible conformations for its alignment within the delta opioid receptor. The data provide evidence that the delta receptor is sensitive to changes in the composition, conformation, and orientation of the side chain of residue 3 of a linear opioid heptapeptide
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