Venom Denaturing with Heat

Question

My friend got stung by a stingray yesterday and the lifeguard quickly stuck her foot into hot water (she said the water burned slightly on contact) and remarkably, she was walking without pain in a hour. I have heard that rattlesnake's bites can be helped by applying heat to denature the proteins. I am assuming this is what happened here, please correct if wrong. Because I am often in areas where immediate help in cases of animal bites/stings is not available, this is important to me as a first response as I get the person to help.

1. What kinds of venom are susceptible to denaturing by heat? How do I know which the previous categories a given venom falls into?
2. Is there a rough temperature I should aim for to denature the venom?
3. How likely is it that I would end up doing more harm by applying heat out of ignorance than doing nothing till I get to help (could be a day or more depending on the location)?

Answer 1

Regarding snake venoms, they tested 28 snake venoms at 100'C: 19/28 of the venoms were still very dangerous after 5 minutes at 100'C.

"Heating all venoms led to the denaturation and loss of some proteins; however, most of the venoms retained a significant number of proteins. Seventeen venoms contained more than seven proteins after heating, whereas five venoms contained only one to three proteins. All but nine of the heated venoms had substantial hemorrhagic activity, and Agkistrodon piscivorus piscivorus venom had very high activity, almost four times that of the second most hemorrhagic venom from Crotalus viridis lutosus."

There is a good chance that land animals have higher heat tolerance spiders and snakes can experience a lot higher heat than marine organisms.

study of marine venoms and hot water says: Sting ray venom is especially fast to denaturize in heat, and most fish spine venoms are. HWI hot wat immersion is recommended for fish spine stings by some organizations. They did tests to find that box jellyfish, sting rays and other sea creatures stings react significantly to HWI.

They tested that 122/138 marine envenomations were improved by HWI from a variety of surveys.

there are 50,000 marine stings a year from 2000 species and about 5 million snake bites, 2mn envonomings and 20-125,000 deaths by snakes every year from 400 species out of 3000 species of snakes which are dangerous to humans.

Dangerous snake and spider bites are generally treated in hospital, and the only wise thing to do is not to not make your blood go around your body very fast by being active after a bite, stay calm and alert.

Answer 2

All venoms are proteins and proteins are chemicals whose shape is determined by the amino acids with the sequence of the protein coding gene. Applying UV radiation or heat can denature it by breaking the chemical interactions amongst the side chains inevitably resulting in a protein which cannot refold upon itself as it has been damaged and cannot cause harm.

Answer 3

Hot water immersion is the best treatment for stings from marine fish, as the above paper says.

However, I do not see that this paper claims the fish venoms denaturize in heat. The above mentioned paper states that immersion of the stung part of the body in hot water alleviates the pain, swelling and other symptoms. It does not prove or offer the mechanism of this action.

That being said, venoms comprised of proteins should be more susceptible to denaturation. The venom of Trachinus draco, dracotoxin has been characterized and it is a single polypeptide. It is also proven that it is sensitive to heat.

But, there is not much research done in fish venoms and not everything is so clear. For instance, from my own experience, I know that Trachinus Draco sting inflicts pain, that is not due to tissue damage alone, but due to some biological mechanism. It is said that this pain can grow so strong, that people far from the coast would sometimes amputate their fingers.

This pain quickly dissapears after immersion in hot water. But, all the research done on the Trachinus draco toxin so far says that this pain is not caused by the dracotoxin itself, but by some other, smaller molecule, that can be dialyzed. Paper from 1962. says it is due to serotonin, but it remains an open question, particularly because all venom extractions so far were made by dissecting tissue around the venom glands, so it could contain parts not usually injected by the fish.