title: Stabilization of alpha-chymotrypsin by covalent immobilization on amine-functionalized superparamagnetic nanogel.
abstract: Stabilization of alpha-chymotrypsin (CT) by covalent immobilization on the amine-functionalized magnetic nanogel was studied. The amino groups containing superparamagnetic nanogel was obtained by Hoffman degradation of the polyacrylamide (PAM)-coated Fe(3)O(4) nanoparticles prepared by facile photochemical in situ polymerization. CT was then covalently bound to the magnetic nanogel with reactive amino groups by using 1-ethyl-3-(3-dimethylaminepropyl) carbodiimide as coupling reagent. The binding capacity was determined to be 61mg enzyme/g nanogel by BCA protein assay. Specific activity of the immobilized CT was measured to be 0.93U/(mgmin), 59.3% as that of free CT. The obtained immobilized enzyme had better resistance to temperature and pH inactivation in comparison to free enzyme and thus widened the ranges of reaction pH and temperature. The immobilized enzyme exhibited good thermostability, storage stability and reusability. Kinetic parameters were determined for both the immobilized and free enzyme. The value of K(m) of the immobilized enzyme was larger than did the free form, whereas the V(max) was smaller for the immobilized enzyme.
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hong
authors.forename: Peijun
authors.initials: P
authors.lastname: Gong
authors.forename: Dongmei
authors.initials: D
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Dong
authors.forename: Side
authors.initials: S
authors.lastname: Yao
mesh_terms: D000588:Amines / Q000737:chemistry / Q000378:metabolism; D002918:Chymotrypsin / Q000737:chemistry*; D004356:Drug Storage; D004789:Enzyme Activation; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D000080385:Nanogels; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D013696:Temperature
chemical_list: D000588:Amines; D004800:Enzymes, Immobilized; D000080385:Nanogels; C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D002918:Chymotrypsin; C117608:alpha-chymotrypsin