A novel amylolytic enzyme from Palaeococcus ferrophilus with malto-oligosaccharide forming ability belonging to subfamily GH13_20

By heterologous expression of a gene from Palaeococcus ferrophilus , a novel recombinant enzyme designated AMPf was obtained and proved to be an amylolytic enzyme with unique catalytic characteristics. The optimal temperature and pH of AMPf were 50 °C and 7.0 respectively. Although sequence analysis and acarbose hydrolysis ability indicated that AMPf belongs to the subfamily GH13_20, interestingly, this enzyme hardly acts on cyclodextrins and pullulan distinguishing it from most enzymes in this subfamily. AMPf hydrolyzes starches to glucose, maltose , maltotriose , and maltotetrose as main products. AMPf mainly liberates glucose from starch with the concentration of 1% (w/v), while it shows malto-oligosaccharide forming ability with higher starch concentration of 4% (w/v). Also, the 4,6-ethylidene-4-nitrophenyl-maltoheptaose hydrolysis ability further indicates the unique combination endo-acting and glucose releasing exo-acting activtity of AMPf. AMPf could utilize maltose and maltotriose to produce malto-oligosaccharides by transglycosylation activity. It was proven AMPf has application protential in malto-oligosaccharides production.