HELP! How will pH 14 affect enzyme structure? If a substance is very alkaline/ basic, e.g. a pH of 14, does this mean that there are near to zero H+ ions (or it is possible to have such a situation where there are zero H+ ions and it is still alkaline) or does it mean there are lots of OH- ions relative to H+ ions? If so, how will this affect enzyme structure in very alkaline/ acidic conditions?

This is a very chemical explanation. Here goes.

$\ce{pH = -log[H+]}$

$\ce{pOH = -log[OH-]}$

$\ce{pH + pOH = 14}$

Therefore, at a $\ce{pH}$ of $14$, $\ce{pOH}$ is zero, so there is 1 mole of $\ce{OH-}$ and $10^{-14}$ moles of $\ce{H+}$ in a liter of your substance.