title: Regulation of lysozyme activity based on thermotolerant protein/smart polymer complex formation.
abstract: Proteins have evolved to acquire highly specialized biological functions and are ideal for various applications in both medicine and biotechnology, although denaturation is one of the major problems in protein chemistry. Here, we show a novel strategy for the regulation and preservation of the enzymatic activity even after heat treatment by the complex formation with a cationic smart copolymer, poly(N,N-diethylaminoethyl methacrylate)-graft-poly(ethylene glycol) (PEAMA-g-PEG). PEAMA-g-PEG suppressed the enzymatic activity of lysozyme completely without any conformational change, indicating complex formation and the capping of the active site of lysozyme by PEAMA-g-PEG. The addition of an anionic polymer, poly(acrylic acid) (PAAc), recovered the inhibited enzymatic activity of the lysozyme/PEAMA-g-PEG complex completely. Surprisingly, even after heating the lysozyme with PEAMA-g-PEG for 20 min at 98 degrees C, the addition of PAAc recovered 80% enzymatic activity of lysozyme. Circular dichroism (CD) spectral analysis clearly indicated that the irreversible inactivation of lysozyme induced by the heat treatment was suppressed by the complex formation with PEAMA-g-PEG.
authors.affiliation: Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1 Ten-noudai, Tsukuba, Ibaraki 305-8573, Japan.
authors.forename: Sumon
authors.initials: S
authors.lastname: Ganguli
authors.forename: Keitaro
authors.initials: K
authors.lastname: Yoshimoto
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Tomita
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakuma
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Matsuoka
authors.forename: Kentaro
authors.initials: K
authors.lastname: Shiraki
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaki
mesh_terms: D006358:Hot Temperature; D008689:Methacrylates / Q000737:chemistry* / Q000494:pharmacology; D008722:Methods; D009113:Muramidase / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry* / Q000494:pharmacology; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000494:pharmacology; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects
chemical_list: D008689:Methacrylates; D009757:Nylons; C109846:poly(2-(diethylamino)ethyl methacrylate); D011092:Polyethylene Glycols; D009113:Muramidase