Inhibitory Study of Ribonuclease L from Aspergillus sp. with Ferric Ion |
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Authors: | Yoshiharu Eto Shigeko Nishioka Hiroyuki Horitsu Mikio Tomoyeda |
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Institution: | 1. Department of Food and Nutrition, Faculty of Home Economics, Chukyo Women’s University, Ohbu, Aichi 474, Japan;2. Department of Agricultural Chemistry, Faculty of Agriculture, Gifu University, Kakamigahara, Gifu 504, Japan |
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Abstract: | Inhibitory study of RNase L with ferric ion was performed to clarify the function of the enzyme. The maximal inhibitory pH of ferric ion for the enzyme is in 3.5 ~ 5.0 and the type of inhibition is found to be competitive with the substrate. The Km for RNA and Ki of ferric ion are 1.54 × 10?1 mg/ml and 22.5 µM, respectively.As the recovery of activity from iron-inactivated RNase L is almost completely realized by dialysis against EDTA solution, the inhibition of RNase L with ferric ion is considered to be a reversible reaction. Moreover, the enzyme is rapidly inactivated by methylene blue- or rose bengal-sensitized photooxidation, but the photoinactivation of RNase L is protected in the presence of the competitive inhibitor, ferric ion. It may reasonably be taken as an evidence that ferric ion attacks the active site of the enzyme. |
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Keywords: | green tea polyphenols colitis hepatotoxicity nephrotoxicity self-protective enzymes |
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