Pullulanase

Pullulanase is a specific kind of glucanase, an amylolytic exoenzyme, that degrades pullulan. It is produced as an extracellular, cell surface-anchored lipoprotein by Gram-negative bacteria of the genus Klebsiella. Type I pullulanases specifically attack a-1,6 linkages, while type II pullulanases are also able to hydrolyse a-1,4 linkages. It is also produced by some other bacteria and archaea. Pullanase is used as a detergent in biotechnology.

Pullulanase (EC 3.2.1.41) is also known as pullulan-6-glucanohydrolase (Debranching enzyme). Its substrate, pullulan, is regarded as a chain of maltotriose units linked by alpha-1,6-glucosidic bonds. Pullulanase will hydrolytically cleave pullulan (alpha-glucan polysaccharides).

Pullulan is an unusual, industrially important polysaccharide in which short alpha-1,4 chains (maltotriose) are connected in alpha-1,6 linkages. Enzymes that cleave alpha-1,6 linkages in pullulan and release maltotriose are called pullulanases although pullulan itself may not be the natural substrate. In contrast, a glycogen debranching enzyme such GlgX, homologous to this family, can release glucose at alpha,1-6 linkages from glycogen first subjected to limit degradation by phosphorylase. Characterized members of this family include a surface-located pullulanase from Streptococcus pneumoniae and an extracellular bifunctional amylase/pullulanase with C-terminal pullulanase activity

Pullulanase - carbohydrate de-branching - proteins. It is found both to the N or the C-termini of of the alpha-amylase active site region. This domain contains several conserved aromatic residues that are suggestive of a carbohydrate binding function.

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