한국산 무우로부터 cationic isoperoxidase $C_3$를 80% $(NH_4)_2SO_4$ 침전, CM-cellulose chromatography, Sephadex G-100 gel filtration 방법 등을 이용하여 전기이동상에서 하나의 띠로 정제하였다. 정제된 효소는 glycoprotein 이었으며 분자량은 SDS-PAGE와 Sephadex G-150 gel filtration에 의하여 약 44,000으로 나타났다. 정제된 isoperoxidase $C_3$는 guaiacol을 기질로 사용한 경우에 최적 pH가 6.0이었으며, guaiacol과 $H_2O_2$에 대한 Km값은 각각 5.6 mM와 0.77 mM이었다. 여러가지 phenolic compound들에 대한 기질 선호도를 조사한 결과 isoperoxidase $C_3$는 scopoletin, esculetin 그리고 ferulic acid에 대해 높은 Km값을 가지며 anionic isoperoxidase $A_2$와 비교해 볼 때 scopoletin과 ferulic acid에 대하여 기질 친화도가 크게 달랐다.
A cationic isoperoxidase, designated $C_3$, was isolated from Korean-radish (Raphanus savatis L.) root. Purification of the enzyme was accomplished by CM-cellulose chromatography and Sephadex G-100 gel filtration. The enzyme was a glycoprotein and its molecular weight was approximately 44,000 as determined by SDS-PAGE and Sephadex G-150 gel filtration. The optimal pH of the purified enzyme was 6.0 for guaiacol and 5.0 for $H_2O_2$. The Km values for guaiacol and $H_2O_2$ were 5.6 mM and 0.77 mM, respectively. The Km values against several naturally occurring phenolic compounds were also determined. In comparison with the anionic isoperoxidase $A_2$ which was previously purified from the same source, $C_3$ had very high Km values for scopoletin and ferulic acid.
