Invertase from Alocasia leaves(Department of Agricultural Chemistry)

クワズイモ葉のインベルターゼの調製方法としては, 硫安塩析よりもアセトン沈澱法が効果的であった。そこで, 20∿40%アセトン濃度で沈澱した, 部分精製の蛋白画分を, インベルターゼ酵素標品として用い, その諸性質を検討した。本酵素は至適pHが5.0でkm値が9mMの酸性インベルターゼであることが明らかとなった。本酵素は1mM水銀イオンによりほぼ完全に失活し, マンガンイオンおよびマグネシウムイオンの阻害をもうけた。また, 至適温度は35℃にあって, 15分間保持の45℃以上の温度ではほとんど活性を失なった。The paper reports the presence and some properties of acid invertase from Alocasia odora C. Koch leaves. Invertase activities for the protein fractions obtained by acetone, ethanol or ammonium sulfate precipitations were determined. The specific activities of acetone fraction, ethanol fraction and ammonium sulfate fraction were 11.9,14.3 and 2.2,respectively, indicating that the activities of the fractions obtained by the two organic solvents were about six times higher than that obtained by ammonium sulfate. Acetone fraction had an almost equivalent value to that of ethanol fraction in specific activity and the former had two times more than the latter in the content of enzyme protein. The fraction precipitated under 20-40% concentration of acetone, containing most of the invertase, was used for examination of the properties of the invertase from alocasia leaves. The invertase present in the leaves was acid invertase, having a pH optimum of 5.0 and almost no activity at alkaline areas. It had an optimum temperature of 35℃ and was inactivated at temperatures higher than 45℃. The enzyme was inhibited by the presence of 1 mM of Hg^, Mn^ and Mg^ and was not affected by that of Ca^, Fe^, Co^ and K^+. The enzyme mainly showed β-fructofuranosidase activity with small level of maltase activity