Binding of Cu+ and Cu2+ with peptides: Peptides = oxytocin, Arg8 -vasopressin, bradykinin, angiotensin-I, substance-P, somatostatin, and neurotensin.

The intrinsic binding ability of 7 natural peptides (oxytocin, arg8 -vasopressin, bradykinin, angiotensin-I, substance-P, somatostatin, and neurotensin) with copper in 2 different oxidation states (CuI/II ) derived from different Cu+/2+ precursor sources have been investigated for their charge-dependent binding characteristics. The peptide-CuI/II complexes, [M – (n-1)H + nCuI ] and [M – (2n-1)H + nCuII ], are prepared/generated by the reaction of peptides with CuI solution/Cu-target and CuSO4 solution and are analyzed by using matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. The MALDI mass spectra of both [M – (n-1)H + nCuI ] and [M – (2n-1)H + nCuII ] complexes show no mass shift due to the loss of ─H atoms in the main chain ─NH of these peptides by Cu+ and Cu2+ deprotonation. The measured m/z value indicates the reduction of CuI/II oxidation state into Cu0 during MALDI processes.
The number and relative abundance of Cu+ bound to the peptides are greater compared with the Cu2+ bound peptides. Oxytocin, arg8 -vasopressin, bradykinin, substance-P, and somatostatin show the binding of 5Cu+ , and angiotensin-I and neurotensin show the binding of 7Cu+ from both CuI and Cu targets, while bradykinin shows the binding of 2Cu2+ , oxytocin, arg8 -vasopressin, angiotensin-I, and substance-P; somatostatin shows the binding of 3Cu2+ ; and neurotensin shows 4Cu2+ binding. The binding of more Cu+ with these small peptides signifies that the bonding characteristics of both Cu+ and Cu2+ are different. The amino acid residues responsible for the binding of both Cu+ and Cu2+ in these peptides have been identified based on the density functional theory computed binding energy values of Cu+ and the fragment transformation method predicted binding preference of Cu2+ for individual amino acids.

Induction of uPA release in human peripheral blood lymphocytes by [deamino-Cysl,D-Arg8]-vasopressin (dDAVP).

  • [deamino-Cys(l),d-Arg(8)]-vasopressin (dDAVP), known to be an arginine vasopressin (AVP) V(2) receptor agonist, is an agent that increases fibrinolytic activity levels in plasma after its infusion into the human body. However, mechanisms underlying an increase and exact localization of the extrarenal dDAVP-responsive V(2) receptor remain unclarified. Two AVP receptors, V(1a) and V(2), and a related oxytocin (OT) receptor were found to be expressed in human lymphocytes. Furthermore, we found an increase of fibrinolytic activity in the medium of peripheral lymphocytes obtained from human volunteers less than 20 min after dDAVP infusion.
  • The increased activity was also detected in the medium after incubating the lymphocytes in the presence of dDAVP in vitro, being highest at 20 min after the incubation. In accord with the increased fibrinolytic activity, the levels of urokinase-type plasminogen activator (uPA) in the medium were also increased. However, there was no significant difference of plasminogen activator inhibitor-1 (PAI-1), pro-uPA, and tissue-type plasminogen activator (tPA) concentrations in the medium between dDAVP treatment and control.
  • When lymphocytes were preincubated with a V(2) receptor antagonist [Adamantaneacetyl(1),O-Et-d-Tyr(2),Val(4),Aminobutyryl(6),Arg(8,9)]-vasopressin, the dDAVP-induced uPA increase was diminished. In contrast, preincubation with a V(1) receptor antagonist, [beta-Mercapto-beta,beta-cyclopentamethylenepropionyl(1),O-Me-Tyr(2),Arg(8)]-vasopressin, prior to dDAVP treatment resulted in a greater increase of the uPA concentration in the medium than with the dDAVP treatment alone. Thus it was suggested that dDAVP may induce uPA release from human lymphocytes via V(2) receptor-mediated reaction, and also via cross-talk between V(1) and V(2) receptors.

[Arg8]-vasopressin-induced responses on coronary and mesenteric arteries of rats with myocardial infarction: the effects of V1a- and V2-receptor antagonists.

After myocardial infarction, plasma levels of [Arg8]-vasopressin rise to recover hemodynamics. The vascular responses to [Arg8]-vasopressin were studied in vitro in isolated hearts and mesenteric artery segments of rats with 1-day and 3-week-old infarcts, in absence and presence of the V1a-receptor antagonist SR-49059 and the V2-receptor antagonist OPC-31260. Vascular responses of coronary arteries were similar in sham and infarcted hearts. On average, coronary flow was maximally decreased by 70 +/- 3% from baseline values of 11.1 +/- 0.3 ml/min, with pD2 values of 10.52 +/- 0.05.
In mesenteric artery segments of sham and infarcted rats, maximal contractile forces, expressed as percentage of contraction to 125 mM KCl, were similar (232 +/- 23% and 239 +/- 8%, respectively). However, pD2 values from infarcted rats (9.22 +/- 0.07) were significantly lower compared with sham (9.55 +/- 0.07) rats. In coronary as well as mesenteric vessels, the vasoconstrictor responses, being more susceptible to SR-49059 (apparent pA2, between 9.12 and 9.82) than to OPC-31260 (apparent pA2, between 6.21 and 6.92), seemed mediated by the V1a receptor. These data indicate that in mesenteric but not in coronary vessels, an altered responsiveness to vasopressin could be observed. Responses are mediated mainly by the V1a receptor.

Structure determination of [Arg8]vasopressin methylenedithioether in dimethylsulfoxide using NMR.

The structure of [Arg8]vasopressin methylenedithioether ([AVP]CH2) has been determined in dimethylsulfoxide-d6. Two-dimensional DQF-COSY and NOESY spectra were measured and used to derive angle and distance constraints for restrained molecular dynamics (MD) calculations. In the MD trajectory, two types of beta-turn structure were found in the region from Tyr2 to Asn5, suggesting an equilibrium between type-I and type-II’ beta-turn structures. When Halpha chemical shifts were used as an additional constraint, the type-I turn was favoured. To validate this result, an independent energy minimization procedure was used, using differences between calculated and observed chemical shifts.
The two approaches gave essentially identical results. It is therefore concluded that the type-I turn predominates in solution. Analysis of calculated chemical shift contributions suggests that the beta-turn structure found in AVP is well preserved in [AVP]CH2, although the pressin ring size is expanded.

[Arg8]-vasopressin-induced increase in intracellular Ca2+ concentration in cultured rat hippocampal neurons.

Changes in intracellular Ca2+ concentration ([Ca2+]i) induced by [Arg8]-vasopressin (AVP) were studied in cultured rat hippocampal neurons by fura-2 fluorometry. AVP (10-1,000 nM) caused a dose-dependent increase in [Ca2+]i. The selective V1 vasopressin receptor agonist [Phe2, Ile3, Orn8]-vasopressin also induced a significant increase in [Ca2+]i, whereas the selective V2 vasopressin receptor agonist [deamino Cys1, D-Arg8]-vasopressin showed no effect. The AVP-induced increase in [Ca2+]i was inhibited by the selective V1 vasopressin receptor antagonist d(CH2)5[Tyr2(Me), Arg8]-vasopressin and nonpeptide V1 antagonist OPC-21268.
On the other hand, no antagonistic effects were observed with the V2 vasopressin antagonist desglycinamide-[d(CH2)5, D-Ile2, Ile4, Arg8]-vasopressin and nonpeptide V2 antagonist OPC-31260. The increase in [Ca2+]i induced by AVP was abolished after removal of extracellular Ca2+. In addition, AVP-induced [Ca2+]i elevation was not affected by treatment with verapamil, which blocked the [Ca2+]i increase induced by an isotonic high K(+)-medium (50 mM). However, omega-conotoxin GVIA completely inhibited the effect of AVP. These results suggested that the AVP-induced [Ca2+]i increase in cultured rat hippocampal neurons is due to influx of Ca2+ through V1 VP receptors coupled with N-type calcium channels.

[Arg8]-Vasopressin

5-00044 CHI Scientific 4 x 5mg Ask for price

(Arg8)-Vasopressin

H-1780.0001 Bachem 1.0mg 181.2 EUR

(Arg8)-Vasopressin

H-1780.0005 Bachem 5.0mg 618 EUR

Arginine Vasopressin ([Arg8] Vasopressin) Antibody

11112-05011 AssayPro 150 ug 175 EUR

Biotin-(Arg8)-Vasopressin

5-00769 CHI Scientific 4 x 1mg Ask for price

Biotin-(Arg8)-Vasopressin

SP-89701-1 Alpha Diagnostics 1 mg 343.2 EUR

[Arg8]-Vasopressin Peptide

20-abx266476 Abbexa
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[Arg8]-Vasopressin Peptide

abx266476-1ml Abbexa 1 ml 537.5 EUR

[Arg8]-Vasopressin Peptide

abx266476-200l Abbexa 200 µl 362.5 EUR

Biotinyl-(Arg8)-Vasopressin

H-5714.0500 Bachem 0.5mg 950.4 EUR

[Arg8]-Vasopressin (4-9)

5-00045 CHI Scientific 4 x 5mg Ask for price

(Arg8)-Vasopressin (4-9)

H-4092.0005 Bachem 5.0mg 356.4 EUR

(Arg8)-Vasopressin (4-9)

H-4092.0025 Bachem 25.0mg 1311.6 EUR

Arginine Vasopressin ([Arg8] Vasopressin) Antibody (Biotin Conjugate)

11112-05021 AssayPro 150 ug 229 EUR

Val-Asp-(Arg8)-Vasopressin

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[Arg8]-Vasopressin (free acid)

5-00046 CHI Scientific 4 x 5mg Ask for price

(Arg8)-Vasopressin (free acid)

H-1775.0005 Bachem 5.0mg 385.2 EUR

(Arg8)-Vasopressin (free acid)

H-1775.0025 Bachem 25.0mg 1430.4 EUR

(Arg8)-Vasopressin Peptide (Biotin)

abx266681-1ml Abbexa 1 ml 375 EUR

(Arg8)-Vasopressin Peptide (Biotin)

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[Arg8]-Vasopressin (4-9) Peptide

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[Arg8]-Vasopressin (4-9) Peptide

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[Arg8]-Vasopressin (4-9) Peptide

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[Arg8]-Vasopressin (free acid) Peptide

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Effects of exogenous [Arg8]-vasopressin on borderline-hypertensive Hiroshima rats.

The interaction between [Arg8]-vasopressin and a vasopressin receptor antagonist, [d(CH2)5(1), O-Me-Tyr2, Arg8]-vasopressin, was examined in Hiroshima rats and normotensive control rats under pentobarbital anesthesia. [Arg8]-vasopressin dose-dependently increased the arterial pressure in both the Hiroshima and control rats, the pressor effect being greater in the Hiroshima rats.
After the administration of a vasopressin antagonist (0.01 mg/kg), which by itself decreased arterial pressure only in the Hiroshima rats, the dose-response curve for [Arg8]-vasopressin was much more greatly shifted to the right in the control rats. These results indicate that with or without a vasopressin antagonist, the exogenous [Arg8]-vasopressin induced more powerful pressor actions in the Hiroshima rats compared to the control rats.

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