Purification and Properties of β-N-Acetyl-D-glucosaminidase from Alimentary Canal of the Silkworm, Bombyx mori(Biological Chemistry)

概要

論文の詳細を見る
β-N-Acetyl-D-glucosaminidase (EC 3.2.1.30) was purified from the alimentary canal of the silkworm, Bombyx mori, by ammonium sulfate fractionation and chromatography with hydroxylapatite, DEAE Bio-Gel A, chromatofocusing, and Sephacryl S-200. The purified enzyme was a single band on disc-PAGE. The molecular weight was 119,000 by gel filtration and 125,000 by SDS-PAGE. The enzyme was separated into two peptides whose apparent molecular weights were 67,500 and 57,500 by SDS-PAGE. The pI was 4.86 by chromatofocusing. The optimum pH was 5.5 to 6.0 and the optimum temperature, 45℃, using pNp-β-GlcNAc as the substrate. The enzyme was stable from pH 5.5 to 8.5 and below 300℃. It was strongly inhibited by HgCl_2. Small N-acetylchitooligomers were as good substrates as pNp-β-GlcNAc, and the enzyme cleaved colloidal chitin to GlcNAc, even though the relative velocity was slow. Smaller N-acetylchitooligomers were preferred substrates with Km 0.787 to 0.056mM, kcat 1013 to 52sec^<-1>, and kcat/Km 1690 to 754mM^<-1> sec^<-1>. The enzyme precipitated in as band with moulting fluid chitobiase antiserum, but not with haemolymph exo-β-N-acetylglucosaminidase antiserum. The results suggest that this enzyme is an exo-type enzyme which is involved in the degradation of chitin to GlcNAc.
社団法人日本農芸化学会の論文
1986-09-23