Carbonic anhydrase II microcrystals suitable for XFEL studies

XFEL structure of carbonic anhydrase II: a comparative study of XFEL, NMR, X-ray and neutron structures

The combination of X-ray free-electron lasers (XFELs) with serial femtosecond crystallography represents cutting-edge technology in structural biology, allowing the study of enzyme reactions and dynamics in real time through the generation of `molecular movies'. This technology combines short and precise high-energy X-ray exposure to a stream of protein microcrystals. Here, the XFEL structure of carbonic anhydrase II, a ubiquitous enzyme responsible for the interconversion of CO2 and bicarbonate, is reported, and is compared with previously reported NMR and synchrotron X-ray and neutron single-crystal structures.

Microcrystal preparation for serial femtosecond X-ray crystallography of bacterial copper amine oxidase

Recent advances in serial femtosecond X-ray crystallography (SFX) using X-ray free-electron lasers have paved the way for determining radiation-damage-free protein structures under nonfreezing conditions. However, the large-scale preparation of high-quality microcrystals of uniform size is a prerequisite for SFX, and this has been a barrier to its widespread application. Here, a convenient method for preparing high-quality microcrystals of a bacterial quinoprotein enzyme, copper amine oxidase from Arthrobacter globiformis, is reported. The method consists of the mechanical crushing of large crystals (5-15 mm3), seeding the crushed crystals into the enzyme solution and standing for 1 h at an ambient temperature of ∼26°C, leading to the rapid formation of microcrystals with a uniform size of 3-5 µm. The microcrystals diffracted X-rays to a resolution beyond 2.0 Å in SFX measurements at the SPring-8 Angstrom Compact Free Electron Laser facility. The damage-free structure determined at 2.2 Å resolution was essentially identical to that determined previously by cryogenic crystallography using synchrotron X-ray radiation.

Protein-crystal detection with a compact multimodal multiphoton microscope

There is an increasing demand for rapid, effective methods to identify and detect protein micro- and nano-crystal suspensions for serial diffraction data collection at X-ray free-electron lasers or high-intensity micro-focus synchrotron radiation sources. Here, we demonstrate a compact multimodal, multiphoton microscope, driven by a fiber-based ultrafast laser, enabling excitation wavelengths at 775 nm and 1300 nm for nonlinear optical imaging, which simultaneously records second-harmonic generation, third-harmonic generation and three-photon excited ultraviolet fluorescence to identify and detect protein crystals with high sensitivity. The instrument serves as a valuable and important tool supporting sample scoring and sample optimization in biomolecular crystallography, which we hope will increase the capabilities and productivity of serial diffraction data collection in the future.

An outlook on using serial femtosecond crystallography in drug discovery

Introduction: X-ray crystallography has made important contributions to modern drug development but its application to many important drug targets has been extremely challenging. The recent emergence of X-ray free electron lasers (XFELs) and advancements in serial femtosecond crystallography (SFX) have offered new opportunities to overcome limitations of traditional crystallography to accelerate the structure-based drug discovery (SBDD) process. Areas covered: In this review, the authors describe the general principles of X-ray generation and the main properties of XFEL beams, outline details of SFX data collection and processing, and summarize the progress in the development of associated instrumentation for sample delivery and X-ray detection. An overview of the SFX applications to various important drug targets such as membrane proteins is also provided. Expert opinion: While SFX has already made clear advancements toward the understanding of the structure and dynamics of several major drug targets, its robust application in SBDD still needs further developments of new high-throughput techniques for sample production, automation of crystal delivery and data collection, as well as for processing and storage of large amounts of data. The expansion of the available XFEL beamtime is a key to the success of SFX in SBDD.

Crystallography and Its Impact on Carbonic Anhydrase Research

X-ray and neutron crystallography are powerful techniques utilized to study the structures of biomolecules. Visualization of enzymes in complex with substrate/product and the capture of intermediate states can be related to activity to facilitate understanding of the catalytic mechanism. Subsequent analysis of small molecule binding within the enzyme active site provides insight into mechanisms of inhibition, supporting the design of novel inhibitors using a structure-guided approach. The first X-ray crystal structures were determined for small, ubiquitous enzymes such as carbonic anhydrase (CA). CAs are a family of zinc metalloenzymes that catalyze the hydration of CO2, producing HCO3 - and a proton. The CA structure and ping-pong mechanism have been extensively studied and are well understood. Though the function of CA plays an important role in a variety of physiological functions, CA has also been associated with diseases such as glaucoma, edema, epilepsy, obesity, and cancer and is therefore recognized as a drug target. In this review, a brief history of crystallography and its impact on CA research is discussed.