Nitrogen Respiration: What Lifeforms Could Be Like

[Katamari]

What would a lifeform that carried nitrogen in blood instead of oxygen be like?

 

[Ygggdrasil]

Our blood has specialized proteins to transport oxygen because oxygen is a critical molecule in our metabolism. Specifically, oxygen acts as an oxidizing agent, allowing our cells to extract energy from the chemical oxidation of fuel molecules such as carbohydrates and fat. In essence, we can gain energy from burning these fuel molecules because the transfer of electrons from the fuel molecules to oxygen is a thermodynamically favorable process and releases energy.

Nitrogen, on the other hand, is a very poor oxidizing agent. Whereas transferring electrons to oxygen to produce water is a favorable process that releases energy, transferring electrons to nitrogen to produce ammonia is an unfavorable process that requires energy. Part of the reason why it is unfavorable to transfer electrons to nitrogen is that nitrogen is a very stable molecule held together by a very strong triple bond.

Therefore, an organism that carries nitrogen in its blood instead of oxygen would be dead (or at least very inefficient at producing energy) because it could not use some of the most efficient metabolic pathways for producing energy from food.

 

[Katamari]

So any living ones would be exceedingly slow moving? What about a life form with nitrogen a critical part in it's hemoglobin equivalent? Still metabolising oxygen, but using nitrogen as a carrier.

 

[Katamari]

A thought occurred- nitrogen based skin pigment.
Spontaneous combustion in UV?

 

[Ygggdrasil]

Nitrogen atoms (not the N₂ molecules in air) are a critical part of hemoglobin. In addition to being a required part of any protein in the body, nitrogen atoms in the heme group of hemoglobin are involved in binding the iron ion. The iron is, of course, the critical part of hemoglobin which allows it to carry oxygen.

 

[Katamari]

I meant a hemoglobin equivalent with a lot more nitrogen and less carbon.

 

[Katamari]

Okay then, different question. Is there any chemical group (Amines, nitrophenols, fluorocarbons etc) that acts as an effective oxidiser and will react in sunlight, forcing these hypothetical creatures to be nocturnal.

 

[mishrashubham]

Okay then, different question. Is there any chemical group (Amines, nitrophenols, fluorocarbons etc) that acts as an effective oxidiser and will react in sunlight, forcing these hypothetical creatures to be nocturnal.

To be used by organisms as an efficient method of extracting energy, the compound has to be readily available in the creature's local environment.

In addition, if the compound is reactive in sunlight with some other atmospheric gas, it would only exist, if at all, in perpetually dark places (such as deep mountain caves).

Even if you do find such a thing, how does its tendency to react under sunlight have any relation to its holder being nocturnal? I hope you are aware that respiration is a constant process; organisms need energy to live, be it day or night.