title: Enhancing protein crystallization through precipitant synergy.
abstract: Suitable conditions for protein crystallization are commonly identified by screening combinations of independent factors that affect crystal formation. Because precipitating agents are prime determinants of crystallization, we investigated whether a systematic exploration of combinations of mechanistically distinct precipitants would enhance crystallization. A crystallization screen containing 64 precipitant mixtures was devised. Tests with ten HIV envelope-related proteins demonstrated that use of precipitant mixtures significantly enhanced both the probability of crystallization as well as the quality of optimized crystals. Tests with hen egg white lysozyme generated a novel C2 crystal from a salt/organic solvent mixture; structure solution at 2 A resolution revealed a lattice held together by both hydrophobic and electrostatic dyad interactions. The results indicate that mechanistically distinct precipitants can synergize, with precipitant combinations adding unique dimensions to protein crystallization.
authors.affiliation: Vaccine Research Center, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Shahzad
authors.initials: S
authors.lastname: Majeed
authors.forename: Gilad
authors.initials: G
authors.lastname: Ofek
authors.forename: Adam
authors.initials: A
authors.lastname: Belachew
authors.forename: Chih-chin
authors.initials: CC
authors.lastname: Huang
authors.forename: Tongqing
authors.initials: T
authors.lastname: Zhou
authors.forename: Peter D
authors.initials: PD
authors.lastname: Kwong
mesh_terms: D000818:Animals; D011232:Chemical Precipitation; D002645:Chickens; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins; D009113:Muramidase