title: Enhanced Heat Stability of α-Chymotrypsin through Single-Enzyme Confinement in Attoliter Liposomes.
abstract: The entrapment of α-chymotrypsin (α-CT) within 70-140 nm liposomes formed from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) leads to an unexpected and remarkable increase in the thermal stability of the enzyme. This finding is based on the observation that heating aqueous suspensions of α-CT-containing POPC liposomes to 80 °C for 30 minutes resulted in partial enzyme inactivation, whereas the same treatment of aqueous solutions of free α-CT inactivated the enzyme completely. The stabilizing effect of enzyme confinement in the attoliter volumes of the liposomes was found to increase with decreasing numbers of α-CT molecules per liposome. Single-enzyme confinement was particularly effective, as intermolecular interactions between heat-denatured α-CT molecules (causing irreversible inactivation) are not possible.
authors.affiliation: Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan. yosimoto@yamaguchi-u.ac.jp.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshimoto
authors.affiliation: Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Yamada
authors.affiliation: Department of Applied Molecular Bioscience, Yamaguchi University, 2-16-1 Tokiwadai, Ube, 755-8611, Japan.
authors.forename: Misaki
authors.initials: M
authors.lastname: Baba
authors.affiliation: Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland. peter.walde@mat.ethz.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Walde
mesh_terms: D000814:Aniline Compounds / Q000032:analysis; D000818:Animals; D001203:Ascomycota / Q000201:enzymology; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry*; D019286:Endopeptidase K / Q000737:chemistry; D006361:Heating; D009842:Oligopeptides / Q000737:chemistry; D010316:Particle Size; D010713:Phosphatidylcholines / Q000737:chemistry; D055550:Protein Stability; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D000814:Aniline Compounds; D009842:Oligopeptides; D010713:Phosphatidylcholines; D053835:Unilamellar Liposomes; C019498:4-nitroaniline; C043307:succinyl-alanyl-alanyl-prolyl-phenylalanine-4-nitroanilide; D002918:Chymotrypsin; C117608:alpha-chymotrypsin; D019286:Endopeptidase K; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: chymotrypsin; compartment; enzymes; liposomes; stability; vesicles