The hydrogen bond cannot form. In fact, we have a negative charge here and a partially negative charge here and those two like charges will basically repel one another. And so what happens is they will begin to dissociate. And that's exactly why at around this range we see a tremendous decrease in the number of DNA molecules that exist in a double helix form. Because around this PH, half of these guanine have lost their age and have been deprotonated. Now, they cannot form those stabilizing hydrogen bonds.