title: Formation of quasi-regular compact structure of poly(methacrylic acid) upon an interaction with alpha-chymotrypsin.
abstract: Structure and dynamic properties of free poly(methacrylic acid) (PMA) and PMA complexed with alpha-chymotrypsin (CT) were studied using the time resolved fluorescence anisotropy technique. We have found that the interaction of PMA with CT induces the formation of a quasi-regular structure of PMA. At a CT/PMA weight ratio of 4:1 the interaction with CT leads to formation of approximately four equal segments of polyelectrolyte, each binding one CT molecule and characterized by an independent rotational mobility. Increase of the CT/PMA weight ratio above 8:1 gives rise to the overall rotation of the whole enzyme-polyelectrolyte complex. In water-ethanol mixtures the mobility of PMA segments containing CT decreases and the structure of the complex becomes even more rigid due to enhancement of the electrostatic interaction between CT and PMA. Formation of the compact and quasi-regular structure of the complex is perhaps the main reason behind the enhancement of enzyme stability and suppression of enzyme aggregation in water-organic cosolvent mixtures.
authors.affiliation: ChemistryDepartment, Moscow State University, 119899 Moscow, Russia. helena_koudriachova@hotmail.com
authors.forename: E V
authors.initials: EV
authors.lastname: Kudryashova
authors.forename: A K
authors.initials: AK
authors.lastname: Gladilin
authors.forename: V A
authors.initials: VA
authors.lastname: Izumrudov
authors.forename: A
authors.initials: A
authors.lastname: van Hoek
authors.forename: A J
authors.initials: AJ
authors.lastname: Visser
authors.forename: A V
authors.initials: AV
authors.lastname: Levashov
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry*; D002942:Circular Dichroism; D004795:Enzyme Stability; D000431:Ethanol / Q000737:chemistry; D005454:Fluorescence Polarization; D007555:Isoxazoles / Q000737:chemistry; D015394:Molecular Structure; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011487:Protein Conformation; D011721:Pyrenes / Q000737:chemistry; D012997:Solvents / Q000737:chemistry
chemical_list: D007555:Isoxazoles; D011109:Polymethacrylic Acids; D011721:Pyrenes; D012997:Solvents; C030613:polymethacrylic acid; C033962:anthranil; D000431:Ethanol; D002918:Chymotrypsin; C117608:alpha-chymotrypsin