牛耳下腺よりの N-アセチルヘキソサミン : 6 燐酸デアセチラーゼの精製と 2, 3 の性質について
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Deacetylation of N-acetylglucosamine 6-phosphate to produce glucosamine 6-phosphate and acetate has been first demonstrated by Matsushita & Takagi by use of the bovine pa rotid gland extract. In the present paper, a procedure was described for the convenient isolation of the enzyme responsible for the deacetylation from the same source and for its purification by several steps of conventional treatment. A method that has been newly developed for the preparation of N-acetylmannosamine kinase from the hog liver was also reported here. The purified enzyme gave a single peak in the elution pattern from DEAE cellulose column and a single spot on paper electrophoresis, suggesting that the enzyme may consist of a single protein. It showed broad pH optima between 8 and 9 in the reaction mixture with conventional buffer systems, demanding no essential cofactor added. Substrate specificity study revealed that it acted not only upon N-acetylglucosamine 6-phosphate but also upon N-acetylmannosamine 6-phosphate at approximately the same velocity and upon N-acetylglucosamine 6-phosphate less efficiently. The Km for the first substance was calculated to be 9.3×10^<-4>M and that for the second 1.42×10^<-3>M respectively. The enzyme activity was considerably inhibited by divalent cations such as Hg^<++>, Cu^<++> and Cd^<++> and in lesser degree by Sn^<++> and Zn^<++>. Parachloromercuribenzoate was also another potent inhibitor of the activity, suggesting that free sulfhydryl groups in the enzyme protein might be involved in its activity. The enzyme was partially activated and stabilized by the presence of reducing agents such as glutathione, cysteine and sodium sulfite, further supporting above concept. The enzyme was distributed, besides the parotid gland, in the submaxillary gland, tracheal cartilage, intestinal canal, lung, pancreas, kidney and liver of the mammals in considerable amount, but sparsely found in tissues of some lower vertebrates examined.
- 九州歯科学会の論文
- 1970-07-31
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