I've been working on the anatomy of my boron based life using alternative biochemistry. But I've recently came across a problem that I can't solve on my own. In oxygen breathing life on earth, the macromolecule known as hemoglobin located in the blood is what transports oxygen throughout the body.
However, my boron based life doesn't breathe oxygen, in fact oxygen is quite dangerous to my species. As it would form strong bonds with the boron which would kill off the life on my planet. Instead, my boron based life breathes methane which is then broken down in their body for the hydrogen. Due to this function in their body, what alternative macromolecule could I use in their blood to transport the hydrogen that doesn't also contain oxygen.
I hope this question is clear enough to answer. If not, let me know in the comments.