Characterization of a novel endopolygalacturonase from Aspergillus niger with unique kinetic properties

[摘要]

We isolated and characterized a new type of endopolygalacturonase (PG)-encoding gene, pgaD, from Aspergillus niger. The primary structure of PGD differs from that of other A. niger PGs by a 136 amino acid residues long N-terminal extension. Biochemical analysis demonstrated extreme processive behavior of the enzyme on oligomers longer than five galacturonate units. Furthermore, PGD is the only A. niger PG capable of hydrolyzing di-galacturonate. It is tentatively concluded that the enzyme is composed of four subsites. The physiological role of PGD is discussed.

[学科分类] 生物化学/生物物理

[关键词] Endopolygalacturonase;Processivity;Methylated oligogalacturonate;Aspergillus niger;PG;endopolygalacturonase;(GalpA)n;oligogalacturonate with degree of polymerization (n);r(GalpA)n;reduced oligogalacturonate with degree of polymerization (n);DE;degree of esterification;BCF;bond cleavage frequency