DNA PHOTOREACTIVATING ENZYME FROM SILKWORM |
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| Authors: | Noriko Muraoka Atsuyuki Okuda‡ Mituo Ikenaga |
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| Institution: | Nutritional Laboratory, Sanyo Gakuen Women's Junior College, Okayama 703;‡Cancer Institute, University of Kyushu School of Medicine, Fukuoka 812;**Department of Fundamental Radiology, Faculty of Medicine, Osaka University, Kita-ku, Osaka 530, Japan |
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| Abstract: | An ammonium-sulfate-precipitable (33–70%) fraction in extracts from eggs of silkworm Bombyx mori contains photoreactivating enzyme that reactivates the transforming activity of UV inactivated Hemophilus influenzae DNA. The action spectrum for in vitro photoreactivation with the enzyme has a broad peak around 365–385 nm, with a shoulder extending to 460 nm. This relatively higher photoreactivation efficiency at wavelengths longer than 450 nm seems to be a unique feature of DNA photoreactivating enzyme of silkworm. Using gel filtration, a mol wt of 42,000 was estimated for the enzyme. Optimum and isoionic pH of the enzyme were 7.2 and 5.4, respectively. These properties of silkworm enzyme are within the range of variations in reported biochemical characteristics of photoreactivating enzymes from different species. |
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