TY - JOUR

T1 - Hydrolytic properties of a β-mannosidase purified from Aspergillus niger

AU - Ademark, Pia

AU - Lundqvist, Jon

AU - Hägglund, Per

AU - Tenkanen, Maija

AU - Torto, Nelson

AU - Tjerneld, Folke

AU - Stålbrand, Henrik

PY - 1999/10/8

Y1 - 1999/10/8

N2 - A β-mannosidase was purified to homogeneity from the culture filtrate of Aspergillus niger. A specific activity of 500 nkat mg-1 and a 53-fold purification was achieved using ammonium sulfate precipitation, anion- exchange chromatography, and gel filtration. The isolated enzyme has an isoelectric point of 5.0 and appears to be a dimer composed of two 135-kDa subunits. It is a glycoprotein and contains 17% N-linked carbohydrate by weight. Maximal activity was observed at pH 2.4-5.0 and at 70°C. The β- mannosidase hydrolyzed β-1,4-linked manno-oligosaccharides of degree of polymerization (DP) 2-6 and also released mannose from polymeric ivory nut mannan and galactomannan. The K(m) and V(max) values for p-nitrophenyl-β-D- mannopyranoside were 0.30 mM and 500 nkat mg-1, respectively. Hydrolysis of D-galactose substituted manno-oligosaccharides showed that the β-mannosidase was able to cleave up to, but not beyond, a side group. An internal peptide sequence of 15 amino acids was highly similar to that of an Aspergillus aculeatus β-mannosidase belonging to family 2 of glycosyl hydrolases.

AB - A β-mannosidase was purified to homogeneity from the culture filtrate of Aspergillus niger. A specific activity of 500 nkat mg-1 and a 53-fold purification was achieved using ammonium sulfate precipitation, anion- exchange chromatography, and gel filtration. The isolated enzyme has an isoelectric point of 5.0 and appears to be a dimer composed of two 135-kDa subunits. It is a glycoprotein and contains 17% N-linked carbohydrate by weight. Maximal activity was observed at pH 2.4-5.0 and at 70°C. The β- mannosidase hydrolyzed β-1,4-linked manno-oligosaccharides of degree of polymerization (DP) 2-6 and also released mannose from polymeric ivory nut mannan and galactomannan. The K(m) and V(max) values for p-nitrophenyl-β-D- mannopyranoside were 0.30 mM and 500 nkat mg-1, respectively. Hydrolysis of D-galactose substituted manno-oligosaccharides showed that the β-mannosidase was able to cleave up to, but not beyond, a side group. An internal peptide sequence of 15 amino acids was highly similar to that of an Aspergillus aculeatus β-mannosidase belonging to family 2 of glycosyl hydrolases.

KW - β-Mannosidase

KW - Aspergillus niger

KW - Hydrolysis

KW - Manno-oligosaccharides

UR - http://www.scopus.com/inward/record.url?scp=0032845641&partnerID=8YFLogxK

U2 - 10.1016/S0168-1656(99)00172-8

DO - 10.1016/S0168-1656(99)00172-8

M3 - Journal article

C2 - 10553664

AN - SCOPUS:0032845641

VL - 75

SP - 281

EP - 289

JO - Journal of Biotechnology

JF - Journal of Biotechnology

SN - 0168-1656

IS - 2-3

ER -