Purification and Properties of a Proteolytic Enzyme,Cathepsin D,from Chicken Muscle |
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Authors: | Kazuo Fukushima Goh Hooi Gnoh Sakae Shinano |
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Affiliation: | Department of Agricultural Chemistry, Faculty of Horticulture, Chiba University |
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Abstract: | Cathepsin D was isolated from crude extract of chicken muscle by the purification procedures of acid- and heat-treatments, ammonium sulfate fractionation, DEAE-Sephadex A-50 column chromatography and Sephadex G-100 gel filtration. The enzyme was purified about 3700 fold and homogeneous in disc-electrophoretic analysis. The molecular weight was found to be about 36,000 and the isoelectric point to be pH 7.3. The best substrate for this enzyme was 6 m urea-denatured casein, and its activity was maximal at pH 3.5 and 40°C. This enzyme was most stable between pH 4 and 5, and its stability was affected by cupric ion. The enzyme activity was markedly inhibited by sodium laurylsulfate and oxidizing agents such as potassium permanganate, N-bromosuccinimide and iodine, and was slightly activated by hydrogen peroxide. The purified cathepsin D was found to be fairly similar to the acid protease from lotus seed, previously reported by the authors. |
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