Effect of temperature on activity (A) and stability (B) of rHps-Phi, rHps, and rPhi. (A) Enzyme activity was assayed under standard conditions at the indicated temperatures. (B) rHps-Phi was dissolved in buffer A containing 1% CHAPS, 50 mM EDTA, and 10% glycerol; rHps and rPhi were dissolved in buffer A. The enzyme solution was incubated at 90°C for the indicated period. Activity of rHps-Phi was assayed by the method used for HPS/PHI. Activities of rHps and rPhi were assayed under the standard conditions. Symbols: circles, rHps-Phi; triangles, rHps; squares, rPhi.