I am performing a DNS assay to estimate pectinase activity, using citrus pectin as the substrate. However, I do not currently have access to D-galacturonic acid, which is typically used to prepare the standard curve for quantifying the amount of reducing sugar released.

I would like to ask:

🔹 Can D-glucose be used as a substitute for D-galacturonic acid to prepare the standard curve in this context? 🔹 If yes, how should the results be reported (e.g., as µmol glucose equivalents)? 🔹 Will using glucose significantly affect the accuracy of enzyme activity determination compared to using galacturonic acid?

I am using a commercial pectinase from Rhizopus and quantifying reducing sugars at 540 nm after DNS treatment.

Any suggestions or insights on best practices for such substitutions — or tips on reporting results correctly — would be greatly appreciated, Thank you.