αC-Conotoxin PrXA (AlphaC-PrXA) is a conotoxin that was originally isolated from the venom of the fish-hunting Conus parius. αC-Conotoxin PrXA is a highly specific inhibitor of the neuromuscular nAChR. It potently antagonizes mouse muscle adult α1/β1/ε/δ nAChR subunits (IC50 = 1.8 nM) as well as fetal mouse muscle α1/β1/γ/δ nAChR subunits (IC50 = 3 nM). αC-Conotoxin PrXA competes with α-bungarotoxin for binding at the α/δ and α/γ nAChR subunit interfaces (with higher affinity however for the α/δ subunit interface such as α-conotoxin GI and α-conotoxin MI). The 3D structure of αC-Conotoxin PrXA is different from other conotoxins that target nAChR and it is most similar to Waglerin-1, a nAChR blocker isolated from a snake venom. αC-Conotoxin PrXA is a useful tool for investigating the structure and physiological role of nAChRs.
Description:
AA sequence: Thr-Tyr-Gly-Ile-Tyr-Asp-Ala-Lys-Pro-Hyp-Phe-Ser-Cys13-Ala-Gly-Leu-Arg-Gly-Gly-Cys20-Val-Leu-Pro-Hyp-Asn-Leu-Arg-Hyp-Lys-Phe-Lys-Glu-NH2
Disulfide bonds: Cys13-Cys20
Length (aa): 32
Formula: C160H249N43O44S2
Molecular Weight: 3541.1 Da
Appearance: White lyophilized solid
Solubility: water or saline buffer
CAS number: not available
Source: Synthetic
Purity rate: > 95 %
Reference:
Diversity of Conus peptides that target the nicotinic acetylcholine receptors
AlphaC-conotoxin PrXA: a new family of nicotinic acetylcholine receptor antagonists. Biochemistry
We have purified a novel paralytic peptide with 32 AA and a single disulfide bond from the venom of Conus parius, a fish-hunting species. The peptide has the following sequence: TYGIYDAKPOFSCAGLRGGCVLPONLROKFKE-NH2, where O is 4-trans-hydroxyproline. The peptide, designated alphaC-conotoxin PrXA (alphaC-PrXA), is the defining member of a new, structurally distinct family of Conus peptides. The peptide is a competitive nAChR antagonist; all previously characterized conotoxins that competitively antagonize nAChRs are structurally and genetically unrelated. (Most belong to the alpha- and alphaA-conotoxin families.) When administered to mice and fish in vivo, alphaC-PrXA caused paralysis and death. In electrophysiological assays, alphaC-PrXA potently antagonized mouse muscle nicotinic acetylcholine receptors (nAChRs), with IC50 values of 1.8 and 3.0 nM for the adult (alpha1beta1 epsilondelta subunits) and fetal (alpha1beta1 gammadelta subunits) muscle nAChR subtypes, respectively. When tested on a variety of ligand-gated and voltage-gated ion channels, alphaC-PrXA proved to be a highly specific inhibitor of the neuromuscular nAChR. The peptide competes with alpha-bungarotoxin for binding at the alpha/delta and alpha/gamma subunit interfaces of the nAChR, with higher affinity for the alpha/delta subunit interface. AlphaC-PrXA is strikingly different from the many conopeptides shown to be nicotinic antagonists; it is most similar in its general biochemical features to the snake toxins known as Waglerins.
Jimenez EC., et al. (2007) AlphaC-conotoxin PrXA: a new family of nicotinic acetylcholine receptor antagonists. Biochemistry. PMID: 17608455
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常用流动相加酸碱后PH的总结，希望大家能够提供一点自己测过的结果，谢谢先
1.直接用固体磷酸钠配制成50mM的磷酸钠溶液，再调pH到7.4；（我们试着用这个做了下，发现挂不上柱）
2.配置磷酸钠盐缓冲液：按NaH2PO4：Na2HPO4以19：81的摩尔比配制成pH7.4的缓冲液？（附一张百度出来的配方
）
3.如果是磷酸钠盐缓冲液，可以直接将50mM的NaH2PO4的水溶液用NaOH调成pH7.4吗？
再者，2和3这两个方法配制的磷酸钠盐缓冲液有什么区别？最终效果是一样的吗？如果不一样，有什么理论的知识支撑呢？个人感觉是分析化学中酸碱理论中的缓冲液那里的知识。求帮忙解答这些疑问。
另外，我还想问一下，pH对于Ni柱对His-tagged的蛋白的分离纯化影响大吗？是怎么影响的？谢谢大家了！
有了源数据之后把源数据按照大小排列，
选中源数据区域-->ALT+A1-->选中图标区右键-->更改图表类型-->散点图
因为是考察不同PH对药物的影响，样品又不好改变其PH值，这种情况怎么办？希望有经验的高手指教。
我的流动相是甲醇-水（90：10）
谢谢赐教！
请进子版按格式发贴，自行修改，谢谢。
由弱酸及其盐、弱碱及其盐组成的混合溶液，能在一定程度上抵消、减轻外加强酸或强碱对溶液酸碱度的影响，从而保持溶液的pH值相对稳定。这种溶液称为缓冲溶液。
:)
我在做一细菌不同酸碱度生长状况时,发现这些奇怪现象:pH=3的培养基灭菌(TSB液体培养基)灭菌后pH上升到到9.2!而原来pH=9.0的降到8.7(基本没多少变化),请问各位大侠,这是什么原因?
一般做不同酸碱度生长实验时,该如何才能防止pH在湿热灭菌后基本不变化?
是否可以理解为纯化水得PH范围为6.3-7.6？能否直接用pH计测量？谢谢!
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