Computational Design of α-Conotoxins to Target Specific Nicotinic Acetylcholine Receptor Subtypes.

Nicotinic acetylcholine receptors (nAChRs) are drug targets for neurological diseases and disorders, but selective targeting of the large number of nAChR subtypes is challenging. Marine cone snail α-conotoxins are potent blockers of nAChRs and some have been engineered to achieve subtype selectivity. This engineering effort would benefit from rapid computational methods able to predict mutational energies, but current approaches typically require high-resolution experimental structures, which are not widely available for α-conotoxin complexes.

Mutations within the selectivity filter reveal that Kv1 channels have distinct propensities to slow inactivate.

Voltage-activated potassium (Kv) channels open in response to membrane depolarization and subsequently inactivate through distinct mechanisms. For the model Shaker Kv channel from Drosophila, fast N-type inactivation is thought to occur by a mechanism involving blockade of the internal pore by the N-terminus, whereas slow C-type inactivation results from conformational changes in the ion selectivity filter in the external pore. Kv channel inactivation plays critical roles in shaping the action potential and regulating firing frequency, and has been implicated in a range of diseases including episodic ataxia and arrhythmias.

ɑO-Conotoxin GeXIVA isomers modulate N-type calcium (Ca 2.2) channels and inwardly-rectifying potassium (GIRK) channels via GABA receptor activation.

αO-Conotoxin GeXIVA is a 28 amino acid peptide derived from the venom of the marine snail Conus generalis. The presence of four cysteine residues in the structure of GeXIVA allows it to have three different disulfide isomers, that is, the globular, ribbon or bead isomer. All three isomers are active at α9α10 nicotinic acetylcholine receptors, with the bead isomer, GeXIVA[1,2], being the most potent and exhibiting analgesic activity in animal models of neuropathic pain.

Interactions of Globular and Ribbon [γ4E]GID with α4β2 Neuronal Nicotinic Acetylcholine Receptor.

The α4β2 nAChR is implicated in a range of diseases and disorders including nicotine addiction, epilepsy and Parkinson's and Alzheimer's diseases. Designing α4β2 nAChR selective inhibitors could help define the role of the α4β2 nAChR in such disease states. In this study, we aimed to modify globular and ribbon α-conotoxin GID to selectively target the α4β2 nAChR through competitive inhibition of the α4(+)β2(-) or α4(+)α4(-) interfaces.

Periplasmic Expression of 4/7 α-Conotoxin TxIA Analogs in Favors Ribbon Isomer Formation - Suggestion of a Binding Mode at the α7 nAChR.

Peptides derived from animal venoms provide important research tools for biochemical and pharmacological characterization of receptors, ion channels, and transporters. Some venom peptides have been developed into drugs (such as the synthetic ω-conotoxin MVIIA, ziconotide) and several are currently undergoing clinical trials for various clinical indications. Challenges in the development of peptides include their usually limited supply from natural sources, cost-intensive chemical synthesis, and potentially complicated stereoselective disulfide-bond formation in the case of disulfide-rich peptides.

Stoichiometry dependent inhibition of rat α3β4 nicotinic acetylcholine receptor by the ribbon isomer of α-conotoxin AuIB.

The ribbon isomer of α-conotoxin AuIB has 10-fold greater potency than the wild-type globular isomer at inhibiting nicotinic acetylcholine receptors (nAChRs) in rat parasympathetic neurons, and unlike its globular isoform, ribbon AuIB only targets a specific stoichiometry of the α3β4 nAChR subtype. Previous electrophysiological recordings of AuIB indicated that ribbon AuIB binds to the α3(+)α3(-) interface within the nAChR extracellular domain, which is displayed by the (α3)(β4) stoichiometry but not by (α3)(β4). This specificity for a particular stoichiometry is remarkable and suggests that ribbon isoforms of α-conotoxins might have great potential in drug design.

Backbone cyclization of analgesic conotoxin GeXIVA facilitates direct folding of the ribbon isomer.

Conotoxin GeXIVA inhibits the α9α10 nicotinic acetylcholine receptor (nAChR) and is analgesic in animal models of pain. α-Conotoxins have four cysteines that can have three possible disulfide connectivities: globular (Cys-Cys and Cys-Cys), ribbon (Cys-Cys and Cys-Cys), or bead (Cys-Cys and Cys-Cys). Native α-conotoxins preferably adopt the globular connectivity, and previous studies of α-conotoxins have focused on the globular isomers as the ribbon and bead isomers typically have lower potency at nAChRs than the globular form.

The neuroprotective and antioxidant activities of protein hydrolysates from grass carp (Ctenopharyngodon idella) skin.

To observe the neuroprotective and antioxidant activities of the grass carp protein hydrolysates (GPH) obtained from grass carp (Ctenopharyngodon idella) skin by enzymatic hydrolysis. GPH prepared using Protamex, at different (5, 10, 15, 20 and 30 %) degrees of hydrolysis (DH) were investigated. The DPPH radial scavenging, reducing power and inhibition of linoleic acid oxidation activities of GPH were significantly improved by a low DH (5 %) compared with those of GPH with a higher DH (p < 0.

Comparative study on acid-soluble and pepsin-soluble collagens from skin and swim bladder of grass carp (Ctenopharyngodon idella).

Background: Collagen has a wide range of applications in food, biomedical and pharmaceutical products.

Results: The collagens in grass carp (Ctenopharyngodon idella) skin and swim bladder were extracted using acetic acid and pepsin. Higher yield of pepsin-soluble collagen (PSC) was obtained from skin (178 g kg(-1)) than from swim bladder (114 g kg(-1)).

Physicochemical responses and quality changes of red sea bream (Pagrosomus major) to gum arabic coating enriched with ergothioneine treatment during refrigerated storage.

The combined effects of gum arabic coating (GA) and ergothioneine (ER) treatment on the sensory and physicochemical characteristics of red sea bream (Pagrosomus major) stored at 4 ± 1 °C for 16 days were investigated. Fish proximate composition, pH value, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), K-value, TCA-soluble peptides, colour, texture profile analyses (TPA), microbiological properties and sensory quality were measured. The results indicate that treatment with gum arabic and ergothioneine (GAER) retarded nucleotide breakdown, lipid oxidation, protein degradation, and reduced microbial growth compare with the control.

Influence of disulfide connectivity on structure and bioactivity of α-conotoxin TxIA.

Cone snails express a sophisticated arsenal of small bioactive peptides known as conopeptides or conotoxins (CTxs). Through evolutionary selection, these peptides have gained the ability to interact with a range of ion channels and receptors, such as nicotinic acetylcholine receptors (nAChRs). Here, we used reversed-phase high performance liquid chromatography (RP-HPLC) and electrospray ionization-mass spectrometry (ESI-MS) to explore the venom peptide diversity of Conus textile, a species of cone snail native to Hainan, China.

Optimal cleavage and oxidative folding of α-conotoxin TxIB as a therapeutic candidate peptide.

Alpha6beta2 nicotinic acetylcholine receptors (nAChRs) are potential therapeutic targets for the treatment of several neuropsychiatric diseases, including addiction and Parkinson's disease. Alpha-conotoxin (α-CTx) TxIB is a uniquely selective ligand, which blocks α6/α3β2β3 nAChRs only, but does not block the other subtypes. Therefore, α-CTx TxIB is a valuable therapeutic candidate peptide.

Expression and secretion of functional recombinant μO-conotoxin MrVIB-His-tag in Escherichia coli.

μO-conotoxin MrVIB is a 31-amino acid peptide containing three disulfide bonds isolated from the venom of Conus marmoreus, which is a selective antagonist of voltage-gated sodium channel (VGSC) Nav1.8 and has a long-lasting analgesic activity. Drug development of MrVIB has long been hindered over 15 years by difficult chemical synthesis and oxidative folding.