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{{chembox
| Watchedfields = changed
| verifiedrevid = 408396032
| ImageFile=Pandinotoxin.JPG
| ImageSize=250
| ImageAlt = Pandinotoxin α
|OtherNames=Pi-2/Pandinotoxin-2 and potassium channel toxin α-KTx 7.1 [[Protein Data Bank|PDB]] {{PDBe|2pta}}.
|Section1= {{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=185529-64-0
  }}
|Section2= {{Chembox Properties
|  Formula=C<sub>169</sub>H<sub>267</sub>N<sub>53</sub> O<sub>48</sub> S<sub>7</sub>
|  MolarMass=4.033,71 g/mol
|  Appearance=
|  Density=
|  MeltingPt=
|  BoilingPt=
|  Solubility=
  }}
}}











'''Pandinotoxins''' are scorpion-toxins, purified from the venom of scorpion [[Pandinus imperator]]. They are selective blockers of [[voltage-gated]] [[potassium]] [[ion channels]] [1]

Table of contents
-1.Source
-2.Chemistry: 
2.1 Family
2.2 Structure and Homology
			2.2.1 Pandinotoxin K α and β
	2.2.2 Pandinotoxin K γ
-3.Target 
-4.Mode of action  
-5.Toxicity 
-6.Therapeutic use
-7.Treatment 
-8.References 

1.Source

Pandinotoxins are derived from the venom of the [[Pandinus imperator]] scorpion. [1] 

2.Chemistry

2.1 Family
The toxins of the family are designated Pandinotoxin (PiTX) K α, PiTX-K β, and PiTX-K γ.[2] They are members of the [[Charybdotoxin]] family (α-Kx family) of [[proteins]]. [1]

2.2 Structure and Homology
2.2.1 Pandinotoxin K α and β
The [[amino acid]] sequences of PiTX-K α and PiTX-K β are identical, except for the seventh amino acid: a [[proline]] in PiTX-K α and a [[glutamic acid]] in PiTX-K β [2] (see Fig.1).

PiTX-K α and PiTX-K β are 35-residue peptides, which are found to have an [[α-helix]] from residues 10 to 21 and two [[β-sheets]] (β 1 is from 26-28, β 2 is from 33-35). One face of the α-helix has been anchored to the β-sheet by three [[sulphide]] bonds which are conserved in all members of the charybdotoxin family (R-K toxins). [1].

PiTX-K α and PiTX-K β have only two β-sheets whereas other members of the family have three additional amino acid residues at the N-terminal portion, which forms a third β-sheet [1]. 

2.2.2 Pandinotoxin K γ
Pandinotoxin K γ is not investigated yet.


3. Target
Pandinotoxins are the most potent inhibitors of the rapidly inactivating A-type Ca2+-independent voltage-gated potassium channels [3], They also block the delayed rectifier, slowly inactivating channels of the subfamily A member 2 (Kv1.2/KCNA2) [1] and they can reversibly block the Shaker B ( [[Shaker gene]] ) potassium-channels (Kv1.1 sub-family) [4].


4. Mode of action
The residue K27, a [[lysine]] at place 27 of the protein sequence, interacts with the voltage sensitivity blocking activity of CTX channels. It is conserved among PiTX-K α and PiTX-K β. This amino acid is located nearby the selectivity filter of the pore [5] and it is responsible for the interaction with A-type channels by being inserted in the pore of the [[ion channels]] [1]. 

The structural differences in the backbone and side chain between PiTX-K α and CTX result in a higher [[affinity]] for A-type channels for PiTX-K α [1].

The affinity for the Shaker B K+ channel is significantly smaller for PiTX-K β in comparison with PiTX-K α due to the changes in the seventh residue [4].

5. Toxicity
No toxic effects have been found yet. 

6. Therapeutic use
PiTX are used in [[cancer]] therapy. Intraplantarly injection of PiTX-K α before or after the administration of [[diclofenac]] produces a significant reduction in spontaneous flinching, mechanical [[allodynia]] and thermal [[hyperalgesia]] in bone cancer rats. Downregulation of PiTX-K α almost completely eliminates diclofenac-induced anti-[[nociception]] [6].

7. Treatment
This is not known yet.



{| style="float: right; clear: right; margin: 0 0 0.5em 1em; background: #ffffff;" class="toccolours" border="0" cellpadding="1" align="right" width="280"
!The Sequence alignment of the Pandinotoxins
|-
| bgcolor="#eeeeee" |
CTXN - Ala - Asp - Val - Pro - Gly - Asn - Tyr - Pro - Leu - Asp - Lys - Asp - Gly - Asn - Thr - Tyr - Thr - Cys - Leu - Glu - Leu - Gly - Glu - Asn - Lys - Asp - Cys - Gln - Lys - Val - Cys - Lys - Leu - His - Gly - Val - Gln - Tyr - Gly - Tyr - Cys - Tyr - Ala - Phe - Ser - Cys - Trp - Cys - Lys - Glu - Tyr - Leu - Asp - Asp - Lys - Asp - Ser - Val - OH
|-
|}