성숙 중 토마토 과실의 ${eta}$-galactosidase의 활성 변화와 정제한 효소의 생화학적 특성을 조사하였다. 성숙단계에 따른 Toatl activity는 다소 증가하는 경향이었으며 DEAE-sephadex A-50 Column chromatography 및 Sephadex G-100 Column chromatography를 통하여 정제한 결과 ${eta}$-galactosidase 3개의 isoenzyme (${eta}$-galactosidase I, II 및 III)을 가지고 있었다. 이들 각 isoenzyme의 성숙에 따른 활성변화를 조사한 결과 Mp에서는 ${eta}$-galactosidase I, II 및 III는 각각 69.8, 31.8 및 170.8이었으나 RP에서는 48.7, 88.4 및 136.8을 각각 나타내어 ${eta}$-gal I과 III은 다소 감소하였으나 ${eta}$-galactosidase II의 활성은 2.8배 증가하였다. ${eta}$-galactosidase I, II 및 III의 최적 pH는 각각 3.9, 4.2 및 3.9였으며 최적 온도는 $60^{circ}C$ $56^{circ}C$ 및 $60^{circ}C$였다. pH3.0~6.0에서 안정하였고 또한 3개의 isoenzyme은 $55^{circ}C$에서 5분간 열처리하였을 때 활성이 50% 소실되었다. 각 isoenzyme은 $Mg^{{+}{+}}$에 의해 활성이 다소 증가되었으나 $Cu^{{+}{+}}$와 SDS에 의해 활성이 30~40% 감소되었으며 $Hg^{{+}{+}}$에 의해서는 완전히 저해되었다. ${eta}$-gal I, II 및 III의 km치는 각각 0.36mM, 0.63mM 및 0.45mM이었으며 반응속도는 기질의 농도가 $6.0{ imes}10^{-5}$(M)까지 급격히 증가하였다.
The activity changes and biochemical properties of ${eta}$-gal in tomato fruits during ripening were investigated. The total activity was increased during ripening and three isoenzymes (${eta}$-gal I, II and III) were purified through DEAE Sephadex A-50 and Sephadex G-100 column chromatography. The activities of ${eta}$gal isoenzymes (${eta}$-gal I, II and III) during ripening were 69.8, 31.8 and 170.0 units in mature green phase, while those were 48.7, 88.4 and 136.8 units in Red phase, respectively. As the ripening proceeded the activities of ${eta}$-gal I and III were some what decreased but the activity of ${eta}$-gal II was incresed more than 2.8 fold. The optimum pH of ${eta}$-gal I, II and III were 3.9, 4.2 and 3.9 and the optimum temperature of those were $60^{circ}C$, $56^{circ}C$ and $60^{circ}C$, respectively. All isoenzymes were stable at pH 3.6~6.0 and lost their activity about 50% when it heated at $55^{circ}C$ for 5 minute. $Mg^{{+}{+}}$-activated the three isoenzymes but $Ca^{{+}{+}}$ and SDS inhibited about 30~40%. $Hg^{{+}{+}}$ inhibited completely. The km value of ${eta}$-gal I, II and III was 0.36mM, 0.63mM and 0.45mM, reaction rate was rapidly increased until the concentration of substrate was $6.0{ imes}10^{-5}M$.
