标题：Isoprenoid-chained lipid EROCOC 17 4 : a new matrix for membrane protein crystallization and a crystal delivery medium in serial femtosecond crystallography
摘要：In meso crystallization of membrane proteins relies on the use of lipids capable of forming a lipidic cubic phase (LCP). However, almost all previous crystallization trials have used monoacylglycerols, with 1-(cis-9-octadecanoyl)-rac-glycerol (MO) being the most widely used lipid. We now report that EROCOC17 4 mixed with 10% (w/w) cholesterol (Fig. 1) serves as a new matrix for crystallization and a crystal delivery medium in the serial femtosecond crystallography of Adenosine A2A receptor (A2AR). The structures of EROCOC17 4-matrix grown A2AR crystals were determined at 2.0 Å resolution by serial synchrotron rotation crystallography at a cryogenic temperature, and at 1.8 Å by LCP-serial femtosecond crystallography, using an X-ray free-electron laser at 4 and 20 °C sample temperatures, and are comparable to the structure of the MO-matrix grown A2AR crystal (PDB ID: 4EIY). Moreover, X-ray scattering measurements indicated that the EROCOC17 4/water system did not form the crystalline LC phase at least down to − 20 °C, in marked contrast to the equilibrium MO/water system, which transforms into the crystalline LC phase below about 17 °C. As the LC phase formation within the LCP-matrix causes difficulties in protein crystallography experiments in meso, this feature of EROCOC17 4 will expand the utility of the in meso method.
其他摘要：Abstract In meso crystallization of membrane proteins relies on the use of lipids capable of forming a lipidic cubic phase (LCP). However, almost all previous crystallization trials have used monoacylglycerols, with 1-( cis -9-octadecanoyl)- rac -glycerol (MO) being the most widely used lipid. We now report that EROCOC 17 4 mixed with 10% (w/w) cholesterol (Fig. 1) serves as a new matrix for crystallization and a crystal delivery medium in the serial femtosecond crystallography of Adenosine A 2A receptor (A 2A R). The structures of EROCOC 17 4 -matrix grown A 2A R crystals were determined at 2.0 Å resolution by serial synchrotron rotation crystallography at a cryogenic temperature, and at 1.8 Å by LCP-serial femtosecond crystallography, using an X-ray free-electron laser at 4 and 20 °C sample temperatures, and are comparable to the structure of the MO-matrix grown A 2A R crystal (PDB ID: 4EIY). Moreover, X-ray scattering measurements indicated that the EROCOC 17 4 /water system did not form the crystalline L C phase at least down to − 20 °C, in marked contrast to the equilibrium MO/water system, which transforms into the crystalline L C phase below about 17 °C. As the L C phase formation within the LCP-matrix causes difficulties in protein crystallography experiments in meso, this feature of EROCOC 17 4 will expand the utility of the in meso method.
