一种新型褐藻胶裂解酶及其截短体对酶学性质的影响OACSTPCD

Alginate oligosaccharides,the degradation products of alginate,display unique physical and chemical properties,as well as excellent biological effects including anti-tumor,growth promotion,immune regulation,thus they have received extensive attention in recent years.Herein,we report our efforts in exploring more effective alginate lyases for the preparation of alginate oligosaccharides.First,microorganisms collected from seaside soil were screened to obtain strains which could degrade alginate.Alginate lyase was then cloned and expressed from the genome of the target strain,and the corresponding catalytic properties were investigated.As a result,a novel endo-type alginate lyase AlgC2m was identified from Paenibacillus lautus A2,which contained 439 amino acids with only 38％of the highest sequence identity.The N-terminal carbohydrate binding module(CBM32)and the C-terminal catalytic domain(CD)were connected by a linker.AlgC2m and its truncated form AlgC2m-CD showed different enzymatic activities(331.05 and 82.47 U/μmol,respectively)and optimum temperatures(45 and 30 ℃,respectively).Moreover,the truncated form AlgC2m-CD demonstrated preference for the degradation of polyG,affording tetrasaccharides with higher degree of polymerization in addition to usual disaccharides and trisaccharides.