title: Heterogeneous nucleation of protein crystals on fluorinated layered silicate.
abstract: Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface.
authors.affiliation: Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Ino
authors.forename: Itsumi
authors.initials: I
authors.lastname: Udagawa
authors.forename: Kazuki
authors.initials: K
authors.lastname: Iwabata
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Takakusagi
authors.forename: Munehiro
authors.initials: M
authors.lastname: Kubota
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kurosaka
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Arai
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Seki
authors.forename: Masaya
authors.initials: M
authors.lastname: Nogawa
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Tsunoda
authors.forename: Fujio
authors.initials: F
authors.lastname: Mizukami
authors.forename: Hayao
authors.initials: H
authors.lastname: Taguchi
authors.forename: Kengo
authors.initials: K
authors.lastname: Sakaguchi
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D011232:Chemical Precipitation; D002645:Chickens; D003460:Crystallization; D054879:Halogenation; D006801:Humans; D008956:Models, Chemical; D009113:Muramidase / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; D011506:Proteins; D017640:Silicates; C099453:saponite; D009113:Muramidase