title: Enzyme stabilization by domain insertion into a thermophilic protein.
abstract: Insufficient kinetic stability of exoinulinase (EI) restricts its application in many areas including enzymatic transformation of inulin for production of ultra-high fructose syrup and oligofructan, as well as fermentation of inulin into bioethanol. The conventional method for enzyme stabilization involves mutagenesis and therefore risks alteration of an enzyme's desired properties, such as activity. Here, we report a novel method for stabilization of EI without any modification of its primary sequence. Our method employs domain insertion of an entire EI domain into a thermophilic scaffold protein. Insertion of EI into a loop of a thermophilic maltodextrin-binding protein from Pyrococcus furiosus (PfMBP) resulted in improvement of kinetic stability (the duration over which an enzyme remains active) at 37 degrees C without any compromise in EI activity. Our analysis suggests that the improved kinetic stability at 37 degrees C might originate from a raised kinetic barrier for irreversible conversion of unfolded intermediates to completely inactivated species, rather than an increased energy difference between the folded and unfolded forms.
authors.affiliation: Othmer-Jacobs Department of Chemical and Biological Engineering, Polytechnic Institute of New York University, 6 MetroTech Center, Brooklyn, NY 11201, USA.
authors.forename: Chung-Sei
authors.initials: CS
authors.lastname: Kim
authors.forename: Brennal
authors.initials: B
authors.lastname: Pierre
authors.forename: Marc
authors.initials: M
authors.lastname: Ostermeier
authors.forename: Loren L
authors.initials: LL
authors.lastname: Looger
authors.forename: Jin Ryoun
authors.initials: JR
authors.lastname: Kim
mesh_terms: D001230:Aspergillus / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D015202:Protein Engineering / Q000379:methods*; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics*; D019711:Pyrococcus / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014508:Urea / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D014508:Urea; D006026:Glycoside Hydrolases; C023086:inulinase