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Functional implications of modifying RyR-activating peptides for membrane permeability

Date

2005

Authors

Dulhunty, Angela
Cengia, Louise
Young, Jaqui
Pace, Suzy M
Lamb, Graham
Harvey, Peta
Chan, Yao-ban
Wimmer, Norbert
Toth, Istvan
Casarotto, Marco

Journal Title

Journal ISSN

Volume Title

Publisher

Nature Publishing Group

Abstract

Our aim was to determine whether lipoamino acid conjugation of peptides that are high-affinity activators of ryanodine receptor (RyR) channels would (a) render the peptides membrane permeable, (b) alter their structure or (a) reduce their activity. The peptides correspond to the A region of the II-III loop of the skeletal dihydropyridine receptor. The lipoamino acid conjugation increased the apparent permeability of the peptide across the Caco-2 cell monolayer by up to ∼20-fold. Nuclear magnetic resonance showed that the α-helical structure of critical basic residues, required for optimal activation of RyRs, was retained after conjugation. The conjugated peptides were more effective in enhancing resting Ca2+ release, Ca2+-induced Ca2+ release and caffeine-induced Ca2+ release from isolated sarcoplasmic reticulum (SR) than their unconjugated counterparts, and significantly enhanced caffeine-induced Ca2+ release from mechanically skinned extensor digitorum longus (EDL) fibres. The effect of both conjugated and unconjugated peptides on Ca2+ release from skeletal SR was 30-fold greater than their effect on either cardiac Ca2+ release or on the Ca2+ Mg2+ ATPase. A small and very low affinity effect of the peptide in slowing Ca2+ uptake by the Ca2+, Mg2+ ATPase was exacerbated by lipoamino acid conjugation in both isolated SR and in skinned EDL fibres. 7 The results show that lipoamino acid conjugation of A region peptides increases their membrane permeability without impairing their structure or efficacy in activating skeletal and cardiac RyRs.

Description

Keywords

Keywords: 1,4 dihydropyridine receptor; amino acid; caffeine; lipoamino acid; ryanodine receptor; unclassified drug; alpha helix; article; binding affinity; calcium transport; cell strain CACO 2; conjugation; controlled study; extensor digitorum longus muscle; huma Ca 2+ release; Cardiac muscle; Lipoamino acid conjugation; Ryanodine receptor; Sarcoplasmic reticulum; Skeletal muscle

Citation

Source

British Journal of Pharmacology

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1038/sj.bjp.0705981

Restricted until

2037-12-31