The pellet was incubated on a shaker at 4 ◦C for 1 h in 15.0 mL
cold 50 mM sodium acetate (CH3COONa) buffer (pH 5) containing
0.5 M NaCl. Following the centrifugation at 15,000 × g for 15 min at
4 ◦C,the supernatant was diluted 1:1 with 50 mM CH3COONa buffer
(pH 5) and was used as a crude enzyme extract for determination
of exo- and endo-PG levels