title: Salvage of failed protein targets by reductive alkylation.
abstract: The growth of diffraction-quality single crystals is of primary importance in protein X-ray crystallography. Chemical modification of proteins can alter their surface properties and crystallization behavior. The Midwest Center for Structural Genomics (MCSG) has previously reported how reductive methylation of lysine residues in proteins can improve crystallization of unique proteins that initially failed to produce diffraction-quality crystals. Recently, this approach has been expanded to include ethylation and isopropylation in the MCSG protein crystallization pipeline. Applying standard methods, 180 unique proteins were alkylated and screened using standard crystallization procedures. Crystal structures of 12 new proteins were determined, including the first ethylated and the first isopropylated protein structures. In a few cases, the structures of native and methylated or ethylated states were obtained and the impact of reductive alkylation of lysine residues was assessed. Reductive methylation tends to be more efficient and produces the most alkylated protein structures. Structures of methylated proteins typically have higher resolution limits. A number of well-ordered alkylated lysine residues have been identified, which make both intermolecular and intramolecular contacts. The previous report is updated and complemented with the following new data; a description of a detailed alkylation protocol with results, structural features, and roles of alkylated lysine residues in protein crystals. These contribute to improved crystallization properties of some proteins.
authors.affiliation: Biosciences Division, Midwest Center for Structural Genomics, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL, 60439, USA.
authors.forename: Kemin
authors.initials: K
authors.lastname: Tan
authors.forename: Youngchang
authors.initials: Y
authors.lastname: Kim
authors.forename: Catherine
authors.initials: C
authors.lastname: Hatzos-Skintges
authors.forename: Changsoo
authors.initials: C
authors.lastname: Chang
authors.forename: Marianne
authors.initials: M
authors.lastname: Cuff
authors.forename: Gekleng
authors.initials: G
authors.lastname: Chhor
authors.forename: Jerzy
authors.initials: J
authors.lastname: Osipiuk
authors.forename: Karolina
authors.initials: K
authors.lastname: Michalska
authors.forename: Boguslaw
authors.initials: B
authors.lastname: Nocek
authors.forename: Hao
authors.initials: H
authors.lastname: An
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Babnigg
authors.forename: Lance
authors.initials: L
authors.lastname: Bigelow
authors.forename: Grazyna
authors.initials: G
authors.lastname: Joachimiak
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Jamey
authors.initials: J
authors.lastname: Mack
authors.forename: Magdalena
authors.initials: M
authors.lastname: Makowska-Grzyska
authors.forename: Natalia
authors.initials: N
authors.lastname: Maltseva
authors.forename: Rory
authors.initials: R
authors.lastname: Mulligan
authors.forename: Christine
authors.initials: C
authors.lastname: Tesar
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
mesh_terms: D000478:Alkylation; D019295:Computational Biology; D003460:Crystallization; D018360:Crystallography, X-Ray; D057166:High-Throughput Screening Assays / Q000379:methods; D008967:Molecular Biology / Q000379:methods*; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins