Is there any tolerance for the pH of buffers used in the β-Glucan Assay Kit (K-BGLU)?

We highly recommend using buffer at pH stated in the booklet. Usually with enzymes, you will get up to 80% of maximal activity with 0.5 pH units of the optimal; e.g. sodium phosphate buffer pH 6.2 to 6.8 and acetate, pH 4.2 to 4.8. 

Product Page (K-BGLU)