Hydroxylamine cleavage buffer

Final concentrations : 2 M hydroxylamine hydrochloride, 4.3 M guanidine hydrochloride, 0.2 M potassium carbonate (pH 9.0)

Hydroxylamine hydrochloride (Analar grade, BDH)

Guanidine hydrochloride (6 M aqueous), prechilled

Potassium carbonate (1 M)

NaOH (50% w/v)

Dissolve 3.5 g of hydroxylamine hydrochloride in 12 ml of prechilled 6 M aqueous guanidine hydrochloride (use an ice bath). Add 2 ml of 50% (w/v) NaOH slowly with vigorous stirring (magnetic stir bar) followed by 5 ml of 1 M potassium carbonate. Adjust the pH to 9.0 with 50% NaOH, and then adjust the volume to 25 ml with 6 M guanidine hydrochloride.

The inclusion of guanidine hydrochloride is reported to improve the efficiency of Asn-Gly cleavage.