AI Article Synopsis
Article Abstract
Three marine alkaloids, purified from Clavelina moluccensis, were structurally identified as lepadiformines A, B, and C and studied on frog atrial myocytes I(K1), using the patch-clamp technique. Lepadiformine A (0.4 to 3.3 microM) blocked I(K1) dose-dependently with an apparent dissociation constant (K(D)) equal to 1.42 microM and a stoichiometry of 0.77. The block is voltage-dependent, suggesting that lepadiformine A occupies a receptor site located at about two-thirds of the membrane depth. The shortening of the aliphatic chain at position C13 of lepadiformine B decreased the potency of the molecule to block I(K1) but not the affinity (K(D) = 1.56 microM) and stoichiometry (0.72). Additional deletion of the oxygenated side chain at C2 in lepadiformine C markedly decreased the inhibitory effect of the molecule. In conclusion, lepadiformine modulates I(K1) response in cardiac muscle. The oxygenated side chain in C2 is implicated in the affinity of lepadiformine, which behaved as an amine, for a receptor located near or inside the I(K1) pore, and the aliphatic chain length at position C13 is involved in the degree of I(K1) blockage.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/np050215s | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Differential superoxide production in phosphorylated neuronal nitric oxide synthase mu and alpha variants.
J Inorg Biochem
February 2024
College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA; Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA. Electronic address:
Neuronal nitric oxide synthase (nNOS) is regulated by phosphorylation in vivo, yet the underlying biochemical mechanisms remain unclear, primarily due to difficulty in obtaining milligram quantities of phosphorylated nNOS protein; detailed spectroscopic and rapid kinetics investigations require purified protein samples at a concentration in the range of hundreds microM. Moreover, the functional diversity of the nNOS isoform is linked to its splice variants. Also of note is that determination of protein phosphorylation stoichiometry remains as a challenge.
View Article and Find Full Text PDFGlycosaminoglycan-binding properties and kinetic characterization of human heparin cofactor II expressed in Escherichia coli.
Anal Biochem
November 2010
Department of Pathology, Vanderbilt University School of Medicine, C3321A Medical Center North, Nashville, TN 37232, USA.
Irreversible inactivation of alpha-thrombin (T) by the serpin, heparin cofactor II (HCII), is accelerated by ternary complex formation with the glycosaminoglycans (GAGs) heparin and dermatan sulfate (DS). Low expression of human HCII in Escherichia coli was optimized by silent mutation of 27 rare codons and five secondary Shine-Dalgarno sequences in the cDNA. The inhibitory activities of recombinant HCII, and native and deglycosylated plasma HCII, and their affinities for heparin and DS were compared.
View Article and Find Full Text PDFSelective chemosensor for copper ions based on fluorescence quenching of a Schiff-base fluorophore.
Appl Spectrosc
July 2010
Department of Analytical Chemistry, Faculty of Sciences, University of Cádiz, P.O. Box 11510, Campus Río S. Pedro, Puerto Real, Cádiz 11510, Spain.
A Schiff base-based fluorescent chemosensor has been studied for divalent copper detection. The formation of 2-hydroxybenzaldehyde benzoylhydrazone-Cu(2+) complex induced a fluorescence quenching of this compound in a medium of water/ethanol (53% v/v) and 0.05 M phosphate buffer (pH 7.
View Article and Find Full Text PDFProperties of the C-terminal tail of human mitochondrial inner membrane protein Oxa1L and its interactions with mammalian mitochondrial ribosomes.
J Biol Chem
September 2010
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
In humans the mitochondrial inner membrane protein Oxa1L is involved in the biogenesis of membrane proteins and facilitates the insertion of both mitochondrial- and nuclear-encoded proteins from the mitochondrial matrix into the inner membrane. The C-terminal approximately 100-amino acid tail of Oxa1L (Oxa1L-CTT) binds to mitochondrial ribosomes and plays a role in the co-translational insertion of mitochondria-synthesized proteins into the inner membrane. Contrary to suggestions made for yeast Oxa1p, our results indicate that the C-terminal tail of human Oxa1L does not form a coiled-coil helical structure in solution.
View Article and Find Full Text PDF86Rb+ efflux mediated by alpha4beta2*-nicotinic acetylcholine receptors with high and low-sensitivity to stimulation by acetylcholine display similar agonist-induced desensitization.
Biochem Pharmacol
October 2010
Institute for Behavioral Genetics, 447UCB, University of Colorado, Boulder, CO 80309, USA.
The nicotinic acetylcholine receptors (nAChR) assembled from alpha4 and beta2 subunits are the most densely expressed subtype in the brain. Concentration-effect curves for agonist activation of alpha4beta2*-nAChR are biphasic. This biphasic agonist sensitivity is ascribed to differences in subunit stoichiometry.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!