α-Chymotrypsin-catalyzed reaction confined in block-copolymer vesicles.
Herein the reactivity of the enzyme α-chymotrypsin in the confinement of polystyrene-block-poly(acrylic acid) (PS-b-PAA) vesicles was investigated. Enzyme and substrate molecules were encapsulated in PS-b-PAA vesicles with internal diameters ranging from 26 nm to 165 nm during the formation of the vesicles. While the loading efficiencies of enzyme and substrate molecules were practically identical for vesicles of identical size, they were found to increase with decreasing vesicle size. The kinetics of the α-chymotrypsin catalyzed hydrolysis of N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin (AMC) was evaluated following the increase of the absorption of the product 7-amino-4-methylcoumarin by UV/Vis spectroscopy. The values of the catalytic turnover number obtained for reactions inside vesicles with different sizes showed an increase of up to fourteen times compared to the bulk value with decreasing vesicle volume, while the values of the Michaelis-Menten constant decreased, respectively. This increase in reactivity of α-chymotrypsin is attributed to the effect of vesicle-wall interactions in the finite encapsulated space, where the reagents could diffuse, leading to enhanced collision frequencies.
Chen
Qi
Q
Department of Materials Science and Technology of Polymers, University of Twente, MESA+Institute for Nanotechnology, PO Box 217, 7500 AE Enschede, The Netherlands.
Rausch
Kristin G
KG
Schönherr
Holger
H
Vancso
G Julius
GJ
D000180:Acrylic Resins / Q000737:chemistry; D055162:Biocatalysis; D002918:Chymotrypsin / Q000737:chemistry*; D003374:Coumarins / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D036103:Nanotechnology; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
D000180:Acrylic Resins; D003374:Coumarins; D011108:Polymers; D011137:Polystyrenes; C006903:carbopol 940; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; C028743:7-amino-4-methylcoumarin