Micro ATR FTIR imaging of hanging drop protein crystallisation

Protein crystallisation is of great importance within structural proteomic projects where considerable time and effort is spent trying to obtain high resolution structural information from the X-ray diffraction of protein crystals. The crystallisation process is largely empirical due to a lack of understanding of crystallisation kinetics and it is often very challenging to obtain crystals of sufficient size and quality for X-ray analysis and data collection. This paper presents the use of micro attenuated total reflection (ATR) – Fourier Transform Infrared (FTIR) spectroscopic imaging as an analytical method for the measurement of the growth of protein crystals using the hanging drop approach. As well as allowing for the measurement of in situ growth of protein crystals, the high spatial resolution of this method allows the detection of micro-crystals. The use of this technique could be very advantageous for protein structural studies since it allows both detection of the growth of small protein crystals and provides chemical information as the crystals form.