Studies on the Peroxidase Activity of Rabbit Hemoglobin = 토끼 Hemoglobi의 Peroxidase 활성에 관한 연구

국문 초록 (Abstract)

토끼 erythrocyte lysate으로부터 hemoglobin을 $(NH_4)_2SO_4$ 분별침전, CM-Sephadex 크로마토그래피, hydroxyapatite 크로마토그래피, Sephadex G-l00 겔 크로마토그래피 방법을 이용하여 순수 정제하였다. 정제한 토끼 hemoglobin은 peroxidase 활성을 나타냈으며 guaiacol과 o-dianisidine을 기질로 사용하였을 경우 식물 peroxidase보다 10배 가량 낮은$K_m$값을 나타냈다. 여러 phenol 화합물들을 기질로 사용하였을 때 토끼 hemoglobin은 caffeic acid, chlorogenic acid, indole-3-acetic acid를 빠르게 산화하였으며, disubstituted phenol 화합물과 methoxylated phenol 화합물들이 rabbit hemoglobin에 대하여 친화력이 큰 것으로 나타났다. Chemical modification 실험결과 토끼 hemoglobin은 iodoacetamide와 N-ethylmaleimide에 의하여 활성이 억제되지 않지만 p-chloromercuribenzoate에 의해서는 활성이 현저히 억제되었다. 또한 식물 peroxidase와는 달리 hemoglobin의 peroxidase 활성은 diethylpyrocarbonate에 의하여 급격히 불활성화 되었다.

다국어 초록 (Multilingual Abstract)

Rabbit hemoglobin was purified by using ammonium sulfate fractionation, CM-Sephadex chromatography, hydroxyapatite chromatography and Sephadex G-100 gel filtration. The purified hemoglobin oxidized various synthetic and naturally occurring phenolic compounds in the presence of $H_2O_2$. The substrate specificity studies indicate that rabbit hemoglobin has about 10 times lower $K_m$ values for guaiacol (0.39 mM) and o-dianisidine (0.09 mM) when compared to those of plant peroxidases. Among natural substrates tested, rabbit hemoglobin catalyzes the oxidation of caffeic acid, chlorogenic acid and indole-3-acetic acid quite rapidly compare to other naturally occurring phenolic compounds such as scopoletin, esculetin, ferulic acid and p-coumaric acid. In general, phenolic compounds having methoxy group appears to have high affinity to rabbit hemoglobin as revealed by their very low $K_m$ values. Chemical modification studies indicate that p-chloromercuribenzoate inactivates the peroxidase activity of rabbit hemoglobin, whereas N-ethylmaleimide or iodoacetamide does not. Furthermore, the peroxidase activity of rabbit hemoglobin is rapidly inactivated by diethylpyrocarbonate, a histidyl selective reagent, unlike plant peroxidases.