Thermodynamic considerations in co-ordination. Part XIV. Formation constants for lead(II)–amino-acid complexes and their use in computing the complexing competition between lead(II) and in vivo essential metal ions, and in computer evaluation of ligands currently employed as lead(II) chelating therapeuticals

[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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19951229 ◽

1995 ◽

Vol 60 (7) ◽

pp. 1229-1235 ◽

Cited By ~ 2

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).

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ATP potently modulates anion channel-mediated excitatory amino acid release from cultured astrocytes

AJP Cell Physiology ◽

10.1152/ajpcell.00438.2001 ◽

2002 ◽

Vol 283 (2) ◽

pp. C569-C578 ◽

Cited By ~ 91

Author(s):

Alexander A. Mongin ◽

Harold K. Kimelberg

Keyword(s):

Amino Acid ◽

Excitatory Amino Acid ◽

Atp Release ◽

Anion Channel ◽

P2y Receptors ◽

Cell Swelling ◽

Channel Blockers ◽

Medium Osmolarity ◽

Subsequent Activation

Volume-dependent ATP release and subsequent activation of purinergic P2Y receptors have been implicated as an autocrine mechanism triggering activation of volume-regulated anion channels (VRACs) in hepatoma cells. In the brain ATP is released by both neurons and astrocytes and participates in intercellular communication. We explored whether ATP triggers or modulates the release of excitatory amino acid (EAAs) via VRACs in astrocytes in primary culture. Under basal conditions exogenous ATP (10 μM) activated a small EAA release in 70–80% of the cultures tested. In both moderately (5% reduction of medium osmolarity) and substantially (35% reduction of medium osmolarity) swollen astrocytes, exogenous ATP greatly potentiated EAA release. The effects of ATP were mimicked by P2Y agonists and eliminated by P2Y antagonists or the ATP scavenger apyrase. In contrast, the same pharmacological maneuvers did not inhibit volume-dependent EAA release in the absence of exogenous ATP, ruling out a requirement of autocrine ATP release for VRAC activation. The ATP effect in nonswollen and moderately swollen cells was eliminated by a 5–10% increase in medium osmolarity or by anion channel blockers but was insensitive to tetanus toxin pretreatment, further supporting VRAC involvement. Our data suggest that in astrocytes ATP does not trigger EAA release itself but acts synergistically with cell swelling. Moderate cell swelling and ATP may serve as two cooperative signals in bidirectional neuron-astrocyte communication in vivo.

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Potentiometric study of enantioselective effects in α-amino acid complexes of copper(II)

Inorganica Chimica Acta ◽

10.1016/s0020-1693(00)83787-1 ◽

1985 ◽

Vol 104 (1) ◽

pp. 63-67 ◽

Cited By ~ 6

Author(s):

I.L. Ulanovski ◽

A.A. Kurganov ◽

V.A. Davankov

Keyword(s):

Amino Acid ◽

Potentiometric Study ◽

Amino Acid Complexes

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