I'm not persuaded to accept this one. True, it's in Merriam-Webster - although with a note saying that it's not one of the 200,000 entries in the free online dictionary, but is only found in the unabridged edition. However, the very few examples I found in the corpora I normally use seemed to be misspelling the protein actin (which is already accepted in Chi).
Actine is also in the OED, with two examples from very old editions of the Encyclopedia Britannica and one more recent quote from the scientific journal Micron.
I feel the word is too technical and obscure.
