Purification and Some Properties of Endo-l,4-β-d-xylanase from a Fresh-water Mollusc, Pomacea insularus (de Ordigny)

Abstract

Endo-1,4-β-d-xylanase (EC 3.2.1.8) was purified from viscera of a fresh-water mollusc, Pomacea insularus (de Ordigny). The purified enzyme, with a molecular weight of 47,000, gave a single protein band in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE). The amino-terminal sequence was Ala-Ala-Gly-Ala-Gly-Val-Thr-Ser-Glu-Lys-Asp-Arg-Leu-Arg-Arg-Ser-Asp-Lys-Thr-Val-His-Val-Asn-. The enzyme was stable from pH about 4.5 to 9.5 and had its maximum activity at pH about 5.5. The purified enzyme produced X2, X3, X4, and larger xylooligosaccharides from birchwood xylan. The enzyme activity was greatly inhibited by Ag⁺, Hg^{2 +}, Cu^{2 +}, N-bromosuccinimide, and p-chloromercuribenzoic acid. On the other hand, the enzyme activity was greatly elevated by the addition of chloride ion.

Key words:

• fresh-water mollusc
• Pomacea insularus
• β-1,4-xylanase
• N-terminal sequence
• xylooligosaccharides