title: Increased thermal and organic solvent tolerance of modified horseradish peroxidase.
abstract: Horseradish peroxidase (HRP) was modified by maleic anhydride and citraconic anhydride. The thermal and organic solvent tolerances of native and modified enzyme were compared. These chemical modifications of HRP increased their thermostability both in aqueous buffer and some organic solvents, and also enhanced their tolerances of some organic solvents. We have studied the unfolding of native and modified HRP by heat to determine the conformational stability. The temperature at the midpoint of thermal denaturation (T(m)) was increased upon modification. Both enthalpy change (DeltaH(m)) and entropy change (DeltaS(m)) for unfolding of modified enzyme at T(m) were decreased compared with native enzyme. Circular dichroism studies proved that these modifications changed the conformation of HRP. The improvements of stability are related to side chain reorientations of aromatics upon both modifications.
authors.affiliation: Biotechnology Research Center and Key Laboratory of Gene Engineering of Ministry of Education, State Key Laboratory of Biocontrol, Zhongshan University, Guangzhou 510275, PR China. lssljz@zsu.edu.cn
authors.forename: Jian-Zhong
authors.initials: JZ
authors.lastname: Liu
authors.forename: Teng-Li
authors.initials: TL
authors.lastname: Wang
authors.forename: Ming-Tao
authors.initials: MT
authors.lastname: Huang
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Song
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Weng
authors.forename: Liang-Nian
authors.initials: LN
authors.lastname: Ji
mesh_terms: D002942:Circular Dichroism; D002949:Citraconic Anhydrides / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004126:Dimethylformamide / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects*; D005663:Furans / Q000494:pharmacology; D006735:Horseradish Peroxidase / Q000737:chemistry* / Q000187:drug effects; D008239:Lysine / Q000031:analogs & derivatives / Q000737:chemistry; D008299:Maleic Anhydrides / Q000737:chemistry; D011487:Protein Conformation / Q000187:drug effects; D012997:Solvents / Q000494:pharmacology
chemical_list: D002949:Citraconic Anhydrides; D005663:Furans; D008299:Maleic Anhydrides; D012997:Solvents; C018674:tetrahydrofuran; D004126:Dimethylformamide; D006735:Horseradish Peroxidase; D008239:Lysine; D004121:Dimethyl Sulfoxide