Abstract
Kc-cells from Drosophila produce two different beta-D-hexosaminidases, a beta-N-acetyl-D-glucosaminidase (E.C.3.2.1.30) and a beta-N-acetyl-D-hexosaminidase (E.C.3.2.1.52), which are also secreted into the medium. The Mr of both enzymes is about 126,000 +/- 9,700; the S-values are 8.37 +/- 0.44. Both enzymes have about the same pH optima at 5.5 and the same thermal stability. The temperature optima are identical (50 degrees C) for both enzymes if p-nitrophenyl-N-acetylglucosaminide is used as a substrate. However, when p-nitrophenyl-N-acetylgalactosaminide is used as the substrate the beta-N-acetyl-D-hexosaminidase has a temperature optimum about 10 degrees C higher. With higher salt concentrations, the activity of the beta-N-acetyl-D-glucosaminidase increases, whereas beta-N-acetyl-D-hexosaminidase is inhibited. Both enzymes also differ in their sensitivity to urea, the beta-N-acetyl-D-hexosaminidase being less sensitive than the beta-N-acetyl-D-glucosaminidase.
