Does tetrodotoxin look like something in the body?

[jackmell]

Blue-ring octopus' have this. It binds to Na channels in nerve cells.

I don't know if you guys know this in here about biochemistry, but it includes a marvelous story of mimicry.

Anyways, I was just wondering if tetrodotoxin looks like something, in the same way that LSD looks like dopamine. Didn't say anything about mimicry in Wikipedia but they just might not know.

 

[SW VandeCarr]

Blue-ring octopus' have this. It binds to Na channels in nerve cells.

I don't know if you guys know this in here about biochemistry, but it includes a marvelous story of mimicry.

Anyways, I was just wondering if tetrodotoxin looks like something, in the same way that LSD looks like dopamine. Didn't say anything about mimicry in Wikipedia but they just might not know.

What you are asking, I think, is does the body provide a natural compound that could competitively block TTX at the neurotoxic receptor site 1 (NXR1)? I doubt it, at least not in sufficient quantities that would be effective. Otherwise TTX wouldn't be so toxic. However there is a class of peptides which does bind to NXR1 and could possibly block TTX. They're are called $\mu$-conopeptides and their interaction with NXR1 neurotoxins is complex, so I would stay away from the Blue Ring Octopus and other TTX making creatures for the time being. The issue isn't so much how the whole molecule looks, but how that portion of the molecule presented to the receptor site looks.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2920548/

 

[jackmell]

What you are asking, I think, is does the body provide a natural compound that could competitively block TTX at the neurotoxic receptor site 1 (NXR1)? I doubt it, at least not in sufficient quantities that would be effective. Otherwise TTX wouldn't be so toxic. However there is a class of peptides which does bind to NXR1 and could possibly block TTX. They're are called $\mu$-conopeptides and their interaction with NXR1 neurotoxins is complex, so I would stay away from the Blue Ring Octopus and other TTX making creatures for the time being. The issue isn't so much how the whole molecule looks, but how that portion of the molecule presented to the receptor site looks.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2920548/

Hi. Thanks for that. Fascinating subject. Here's a quote:

"TTX is thought to occupy a site within the vestibule of the ion channel near the extracellular end of the channel pore, and, by binding to this site, to occlude the permeation pathway of sodium ions through the pore."

I suppose perhaps I don't understand the physiology well enough. I thought the gate was normally controlled by various molecules which open and close it and that maybe TTX, or a particular part of TTX resembled the active end of the normal molecule which closed it and had a greater affinity to the active site so thus blocked the normal agent from controlling the gate.

 

[SW VandeCarr]

I suppose perhaps I don't understand the physiology well enough. I thought the gate was normally controlled by various molecules which open and close it and that maybe TTX, or a particular part of TTX resembled the active end of the normal molecule which closed it and had a greater affinity to the active site so thus blocked the normal agent from controlling the gate.

The sodium channel has both a pore and a gate, although they work closely together. TTX apparently physically blocks the pore superseding the gating function. Voltage gated channels typically are selective for sodium, potassium or calcium. Ion filtering is a function of the pore. The gate closes to ion flux with inactivation of the channel as during the refractory period following an action potential.

http://jp.physoc.org/content/590/11/2577.full.pdf+html

 

[LudusRex]

I can confirm that tetrodotoxin does not physically resemble any known substance in the human body. However, its effect on the body is due to its ability to bind to sodium channels in nerve cells, which disrupts the normal function of these cells and can lead to paralysis and potentially death. This mechanism of action is similar to other substances that also target sodium channels, such as local anesthetics.

The mention of mimicry in relation to tetrodotoxin may refer to its presence in certain species, such as the blue-ring octopus, for defensive purposes. These animals are able to produce their own tetrodotoxin or acquire it through their diet, and it serves as a form of protection against predators. However, this is not the same type of mimicry seen with LSD and dopamine, which involves structural similarity between the two substances.

Overall, while tetrodotoxin does not physically resemble anything in the body, its mode of action and presence in certain species does involve a form of mimicry for survival. Further research is needed to fully understand the role of tetrodotoxin in these organisms and its potential uses in medicine.