사과 겹무늬썩음병균이(Botryosphaeria dothidea) 생성하는 세포벽 분해효소인 endopolygalaturonase를 억제하는 polygalacturonase-inhibiting protein (PGIP)를 사과 과실로부터 분리하였다. 분리되어진 사과 PGIP는 사과 겹무늬썩음병균이 생성하는 PG에 대하여 혼합형의 저해를 나타내었다. PGIP의 반응 최적온도는 $40^{circ}C$이며 최적 pH는 5.0이었다. 이 효소는 $60^{circ}C$까지는 비교적 안정하였으나 $70^{circ}C$에서는 효소의 활성이 완전히 억제되었으며 pH 4.0에서 8.0까지는 안정하였다. PGIP는 $K^+$, $Cu^{2+}$, $Mg^{2+}$, $Ca^{2+}$ 과 $Zn^{2+}$ 등의 금속이온과 SDS 그리고 CDTA에 의해 효소의 활성이 저해되었다.
An apple polygalacturonase-inhibiting protein (PGIP), that specifically inhibited endopolygalacturonase (PG, EC 3.2.1.15) from Botryosphaeria dothidea, was purified from B. dothidea infected apple (Malus domestica cv. Fuji) fruits. The apple PGIP was a mixed-type inhibitor of PG from B. dothidea. Optimal temperature for the maximum enzyme activity was $40^{circ}C$, and optimum pH of the purified PGIP was pH 5.0. PGIP was stable up to temperature of $60^{circ}C$ and was completely suppressed after heating at $70^{circ}C$ for 10 min, PGIP was stable at pH between 4 and 8. Inhibition of PG by PGIP was reduced by $K^+$, $Cu^{2+}$, $Mg^{2+}$, $Ca^{2+}$ and $Zn^{2+}$ metal ion, sodium dodecyl sulfate (SDS) and 1,2-diaminocyclohexane tetra acetate (CDTA).
