Cell-Free Synthesis of Selenoproteins in High Yield and Purity for Selective Protein Tagging

The selenol group of selenocysteine is much more nucleophilic than the thiol group of cysteine. Selenocysteine residues in proteins thus offer reactive points for rapid post-translational modification. Herein, we show that selenoproteins can be expressed in high yield and purity by cell-free protein synthesis by global substitution of cysteine by selenocysteine. Complete alkylation of solvent-exposed selenocysteine residues was achieved in 10 minutes with 4-chloromethylene dipicolinic acid (4Cl-MDPA) under conditions that left cysteine residues unchanged even after overnight incubation. Gd^III−Gd^III distances measured by double electron–electron resonance (DEER) experiments of maltose binding protein (MBP) containing two selenocysteine residues tagged with 4Cl-MDPA-Gd^III were indistinguishable from Gd^III−Gd^III distances measured of MBP containing cysteine reacted with 4Br-MDPA tags.     

Heat Propagation in Deformable Polycrystalline Metals with Grain-Size Variation

Russian Engineering Research - Attention focuses on the heat propagation in metal polycrystals where the grain or subgrain size affects the strengthening—as a result of surface plastic...     

Ball-End Mill with a Loxodromic Cutting Edge

Russian Engineering Research - Attention focuses on the design of a ball-end mill whose spherical section has a loxodromic cutting edge. The grinding width and depth required to obtain the rake and...