Fig. 3

Effect of temperature and pH on CmNAGase. a The optimal pH of CmNAGase. The optimal pH was determined in 50 mM solutions of various buffers within the pH range of 3.5–10.0 [filled square, citrate buffer (pH 3.0–6.0); filled circle, phosphate buffer (pH 6.0–7.5); filled inverted triangle, Tris–HCl buffer (pH 7.0–9.0)]. b The stability of CmNAGase at various pH values. To determine pH stability, the enzyme was incubated at 35 °C for 96 h with various pH buffers, and the residual activities were measured [filled inverted triangle, 4.7 (citrate buffer); open square, 5.4 (citrate buffer); open diamond, 6.0 (citrate buffer); open circle, 7.0 (phosphate buffer); filled circle, 8.0 (Tris–HCl buffer); open square, 9.0 (Tris–HCl buffer)]. c The optimal temperature of CmNAGase. The temperature optimum was determined at different temperatures (25–60 °C) in 50 mM sodium citrate (pH 5.4) of the recombinant CmNAGase. d The stability of CmNAGase at different temperatures. To determine the thermostability, the enzyme was treated in 50 mM sodium citrate (pH 5.4) for 12 h at different temperatures; the residual activity was measured at pH 5.4 and 40 °C (filled square, 30 °C; filled circle, 35 °C; open triangle 40 °C; filled inverted triangle, 45 °C)