Enhancing the peroxidase activity and decreasing the protease activity of ficin with rational modification and its application to one-step colorimetric detection of glucose.

Ficin has dual enzyme activity, i.e., protease and peroxidase-like activity. In some respects, its application is limited by the protease activity of ficin. Herein, we used tris (2-carboxyethyl) phosphine hydrochloride (TCEP) to break the three pairs of disulfide bonds of ficin, and then blocked the free thiol groups with N-ethylmaleimide (NEM) to synthesize ficin-TN. The results showed that ficin-TN had increased peroxidase-like activity and reduced protease activity. According to this phenomenon, we have exploited a colorimetric method with high sensitivity and selectivity for the one-step detection of glucose. Comparing with ficin, ficin-TN has wider detection range (0.1-300 μM) and lower detection limit (88 nM), and our method is simpler and more timesaving than other two-step methods. Furthermore, the actual appliances of ficin-TN for glucose detection in human serum have been illustrated with satisfied result, suggesting that its promising utilization in various fields.