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Venom as a form of chemical prey capture is a key innovation that has underpinned the explosive radiation of the advanced snakes (Caenophidia). Small venom proteins are often rich in disulfide bonds thus facilitating stable molecular scaffolds that present key functional residues on the protein surface. New toxin types are initially developed through the venom gland over-expression of normal body proteins, their subsequent gene duplication and diversification that leads to neofunctionalisation as random mutations modify their structure and function. This process has led to preferentially selected (privileged) cysteine-rich scaffolds that enable the snake to build arrays of toxins many of which may lead to therapeutic products and research tools. This review focuses on cysteine-rich small proteins and peptides found in snake venoms spanning natriuretic peptides to phospholipase enzymes, while highlighting their three-dimensional structures and biological functions as well as their potential as therapeutic agents or research tools. [ABSTRACT FROM AUTHOR]

Venoms comprise of complex mixtures of peptides evolved for predation and defensive purposes. Remarkably, some carnivorous cone snails can inject two distinct venoms in response to predatory or defensive stimuli, providing a unique opportunity to study separately how different ecological pressures contribute to toxin diversification. Here, we report the extraordinary defensive strategy of the Rhizoconus subgenus of cone snails. The defensive venom from this worm-hunting subgenus is unusually simple, almost exclusively composed of αD-conotoxins instead of the ubiquitous αA-conotoxins found in the more complex defensive venom of mollusc- and fish-hunting cone snails. A similarly compartmentalized venom gland as those observed in the other dietary groups facilitates the deployment of this defensive venom. Transcriptomic analysis of a Conus vexillum venom gland revealed the αD-conotoxins as the major transcripts, with lower amounts of 15 known and four new conotoxin superfamilies also detected with likely roles in prey capture. Our phylogenetic and molecular evolution analysis of the αD-conotoxins from five subgenera of cone snails suggests they evolved episodically as part of a defensive strategy in the Rhizoconus subgenus. Thus, our results demonstrate an important role for defence in the evolution of conotoxins. [ABSTRACT FROM AUTHOR]

Background and Purpose: ω-Conotoxins CVIE and CVIF (CVIE&F) selectively inhibit Cav2.2 channels and are lead molecules in the development of novel analgesics. At physiological membrane potentials, CVIE&F block of Cav2.2 channels is weakly reversible. To improve reversibility, we designed and synthesized arginine CVIE&F analogues in which arginine was substituted for lysine at position 10 ([R10K]CVIE&F), and investigated their serum stability and pharmacological actions on voltage-gated calcium channels (VGCCs).Experimental Approach: Changes in peptide structure due to R10K substitution were assessed by NMR. Peptide stability in human serum was analysed by reversed-phase HPLC and MS over a 24 h period. Two-electrode voltage-clamp and whole-cell patch clamp techniques were used to study [R10K]CVIE&F effects on VGCC currents in Xenopus oocytes and rat dorsal root ganglion neurons respectively.Key Results: R10K substitution did not change the conserved ω-conotoxin backbone conformations of CVIE&F nor the ω-conotoxin selectivity for recombinant or native Cav2.2 channels, although the inhibitory potency of [R10K]CVIF was better than that of CVIF. At -80 mV, the R10K chemical modification significantly affected ω-conotoxin-channel interaction, resulting in faster onset kinetics than those of CVIE&F. Heterologous and native Cav2.2 channels recovered better from [R10K]CVIE&F block than CVIE&F. In human serum, the ω-conotoxin half-lives were 6-10 h. CVIE&F and [R10K]CVIE&F were more stable than CVID.Conclusions and Implications: R10K substitution in CVIE&F significantly alters the kinetics of ω-conotoxin action and improves reversibility without diminishing conotoxin potency and specificity for the Cav2.2 channel and without diminishing the serum stability. These results may help generate ω-conotoxins with optimized kinetic profiles for target binding. [ABSTRACT FROM AUTHOR]

Background and Purpose ω-Conotoxins CVIE and CVIF ( CVIE& F) selectively inhibit Cav2.2 channels and are lead molecules in the development of novel analgesics. At physiological membrane potentials, CVIE& F block of Cav2.2 channels is weakly reversible. To improve reversibility, we designed and synthesized arginine CVIE& F analogues in which arginine was substituted for lysine at position 10 ([ R10K] CVIE& F), and investigated their serum stability and pharmacological actions on voltage-gated calcium channels ( VGCCs). Experimental Approach Changes in peptide structure due to R10K substitution were assessed by NMR. Peptide stability in human serum was analysed by reversed-phase HPLC and MS over a 24 h period. Two-electrode voltage-clamp and whole-cell patch clamp techniques were used to study [ R10K] CVIE& F effects on VGCC currents in X enopus oocytes and rat dorsal root ganglion neurons respectively. Key Results R10K substitution did not change the conserved ω-conotoxin backbone conformations of CVIE& F nor the ω-conotoxin selectivity for recombinant or native Cav2.2 channels, although the inhibitory potency of [ R10K] CVIF was better than that of CVIF. At −80 mV, the R10K chemical modification significantly affected ω-conotoxin−channel interaction, resulting in faster onset kinetics than those of CVIE& F. Heterologous and native Cav2.2 channels recovered better from [ R10K] CVIE& F block than CVIE& F. In human serum, the ω-conotoxin half-lives were 6−10 h. CVIE& F and [ R10K] CVIE& F were more stable than CVID. Conclusions and Implications R10K substitution in CVIE& F significantly alters the kinetics of ω-conotoxin action and improves reversibility without diminishing conotoxin potency and specificity for the Cav2.2 channel and without diminishing the serum stability. These results may help generate ω-conotoxins with optimized kinetic profiles for target binding. [ABSTRACT FROM AUTHOR]

Chronic pain affects approximately 20% of people worldwide and places a large economic and social burden on society. Despite the availability of a range of analgesics, this condition is inadequately treated, with complete alleviation of symptoms rarely occurring. In the past 30 years, the voltage-gated calcium channels (VGCCs) have been recognized as potential targets for analgesic development. Although the majority of the research has been focused on Ca(v) 2.2 in particular, other VGCC subtypes such as Ca(v) 3.2 have recently come to the forefront of analgesic research. Venom peptides from marine cone snails have been proven to be a valuable tool in neuroscience, playing a major role in the identification and characterization of VGCC subtypes and producing the first conotoxin-based drug on the market, the ω-conotoxin, ziconotide. This peptide potently and selectively inhibits Ca(v) 2.2, resulting in analgesia in chronic pain states. However, this drug is only available via intrathecal administration, and adverse effects and a narrow therapeutic window have limited its use in the clinic. Other Ca(v) 2.2 inhibitors are currently in development and offer the promise of an improved route of administration and safety profile. This review assesses the potential of targeting VGCCs for analgesic development, with a main focus on conotoxins that block Ca(v) 2.2 and the developments made to transform them into therapeutics. [ABSTRACT FROM AUTHOR]

α-Conotoxins that are thought to act as antagonists of nicotinic acetylcholine receptors (nAChRs) containing α3-subunits are efficacious in several preclinical models of chronic pain. Potent interactions of Vc1.1 with other targets have suggested that the pain-relieving actions of α-conotoxins might be mediated by either α9α10 nAChRs or a novel GABA(B) receptor-mediated inhibition of N-type calcium channels. Here we establish that three α-conotoxins, Vc1.1, AuIB and MII have distinct selectivity profiles for these three potential targets. Their potencies after intramuscular administration were then determined for reversal of allodynia produced by partial nerve ligation in rats. Vc1.1, which potently inhibits α9α10 nAChRs and GABA(B)/Ca(2+) channels but weakly blocks α3β2 and α3β4 nAChRs, produced potent, long-lasting reversal of allodynia that were prevented by pre-treatment with the GABA(B) receptor antagonist, SCH50911. α-Conotoxin AuIB, a weak α3β4 nAChR antagonist, inhibited GABA(B)/Ca(2+) channels but did not act on α9α10 nAChRs. AuIB also produced reversal of allodynia. These findings suggest that GABA(B) receptor-dependent inhibition of N-type Ca(2+) channels can mediate the sustained anti-allodynic actions of some α-conotoxins. However, MII, a potent α3β2 nAChR antagonist but inactive on α9α10 and α3β4 nAChRs and GABA(B)/Ca(2+) channels, was demonstrated to have short-acting anti-allodynic action. This suggests that α3β2 nAChRs may also contribute to reversal of allodynia. Together, these findings suggest that inhibition of α9α10 nAChR is neither necessary nor sufficient for relief of allodynia and establish that α-conotoxins selective for GABA(B) receptor-dependent inhibition of N-type Ca(2+) channels relieve allodynia, and could therefore be developed to manage chronic pain. [ABSTRACT FROM AUTHOR]

Milk proteins have been studied continuously for over 50 years. Knowledge of this complex protein system has evolved incrementally in recent decades, largely coinciding with advances in technology. Proteomics and associated technologies have the potential to facilitate further advances in our knowledge of milk proteins. Proteomics allows for the detection, identification and characterization of milk proteins. More importantly, proteomics facilitates the analysis of large numbers of milk proteins simultaneously.In the first part of this review we provide a description of the key techniques used within proteomic methodologies, with an emphasis on their general uses within proteomics. In the second part we summarize recent applications of proteomics to milk proteins and highlight the potential for new and rapid advances in the analysis of milk proteins. In particular, we emphasise the effectiveness of two-dimensional gel electrophoresis in combination with various mass spectrometry techniques for the detailed characterization of milk proteins. [Copyright &y& Elsevier]

Abstract: The activity of α-conotoxin (α-CTX), ImI, from the vermivorous marine snail Conus imperialis, has been studied on mammalian nicotinic receptors on bovine chromaffin cells and at the rat neuromuscular junction. Synthetic α-CTX ImI was a potent inhibitor of the neuronal nicotinic response in bovine adrenal chromaffin cells (IC50 = 2.5 μM, log IC50 = 0.4 ± 0.07), showing competitive inhibition of nicotine-evoked catecholamine secretion. α-CTX ImI also inhibited nicotine-evoked 45Ca2+ uptake but not 45Ca2+ uptake stimulated by 56 mM K+. In contrast, α-CTX ImI had no effect at the neuromuscular junction over the concentration range 1-20 μM. Bovine chromaffin cells are known to contain the α3β4, α7, and (possibly) α3β4α5 subtypes. However, the secretory response of bovine chromaffin cells is not inhibited by α-bungarotoxin, indicating that α7 nicotinic receptors are not involved. We propose that α-CTX ImI interacts selectively with the functional (α3β4 or α3β4α5) nicotinic acetylcholine receptor to inhibit the neuronal-type nicotinic response in bovine chromaffin cells. [ABSTRACT FROM AUTHOR]

The article presents an abstract of the research paper "Effect of Conantokins on the Spermine Modulation of Glutamate-NMDA Sites in Normal and Alzheimer Disease Human Cerebral Cortex." The research found that the subunit composition of NMDA sites is locally variable and selective differences between controls and Alzheimer's disease cases in key brain regions.