I'm intrigued to know why you would want to do such a thing?

To chelate Ca/Mg...?

Hi,

is there a specific reason for you to specifically not use EDTA, as it is the generally accepted standard for nuclease inhibition via chelation? If not, I'd highly recommend to stick to the established buffer compositions.

In theory it should work, however consider the potential side-effects, such as pH shift from the usually alkaline (~ pH 13) buffer and differences in chelating efficiency, possibly leaving DNA prone to enzymatic breakdown.