title: Improvement of crystal quality by surface mutations of beta-lactamase Toho-1.
abstract: The beta-lactamase Toho-1 exhibits a strong tendency to form merohedrally twinned crystals. Here, the crystal quality of Toho-1 was improved by using surface modification to remove a sulfate ion involved in crystal packing. The surface-modified Toho-1 variant (R274N/R276N) was crystallized under similar conditions to those used for wild-type Toho-1. R274N/R276N did not form merohedrally twinned crystals. The crystals diffracted to a significantly higher resolution (approximately 0.97 A) than the wild-type crystals (1.65 A); they belonged to the same space group and had almost identical unit-cell parameters to those of wild-type Toho-1.
authors.affiliation: RIKEN SPring-8 Center, Harima Institute, Kouto, Sayo, Hyogo 679-5148, Japan. t.shimamura@mfour.med.kyoto-u.ac.jp
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Shimamura
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Nitanai
authors.forename: Takuro
authors.initials: T
authors.lastname: Uchiyama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsuzawa