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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: Biotechnol Appl Biochem. 2011 Oct 28;58(6):391–396. doi: 10.1002/bab.52

Figure 1.

Figure 1

Labeling and pH optimum of rhIDU. (A) Polyacrylamide gel electrophoresis (4–20%) analysis of rhIDU (IDU) before and after the labeling process. Upper panel shows unstained gel with Alexa Fluor 680 labeled protein (IDU-AF680) clearly visible to the naked eye (DOL of 3.1). Lower panel is the same gel after staining with coomassie blue. (B) Labeled (DOL 3.1) or unlabeled IDU were diluted to 16 μg/ml in 200 mM/100 mM phosphate-citrate buffer at the indicated pHs (2.4–8.0) and immediately assayed for enzyme activity towards the artificial fluorogenic substrate 4-MUI for 15 minutes at 22 °C. Relative activity for each enzyme was plotting from an average of three independent experiments where the maximally observed activity was defined as 100%.