Challenges and opportunities for new protein crystallization strategies in structure-based drug design.

Structure-based drug design (SBDD) has emerged as a valuable pharmaceutical lead discovery tool, showing potential for accelerating the discovery process,while reducing developmental costs and boosting potencies of the drug that is ultimately selected. SBDD is an iterative, rational, lead compound sculpting process that involves both the synthesis of new derivatives and the evaluation of their binding to the target structure either through computational docking or elucidation of the target structure as a complex with the lead compound. This method heavily relies on the production of high resolution(< 2 Å) 3D structures of the drug target, obtained through X-ray crystallographic analysis, in the presence or absence of the drug candidate.

Selective detection of protein crystals by second harmonic microscopy.

The unique symmetry properties of second harmonic generation (SHG) microscopy enabled sensitive and selective imaging of protein microcrystals with negligible contributions from solvated proteins or amorphous protein aggregates. In studies of microcrystallites of green fluorescent protein (GFP) prepared in 500 pL droplets, the SHG intensities rivaled those of fluorescence, but with superb selectivity for crystalline regions. GFP in amorphous aggregates and in solution produced substantial background fluorescence, but no detectable SHG.