Secondary Structure Estimation Using FTIR Spectroscopy

Can FTIR spectroscopy determine secondary structure?

Infrared spectroscopy is an effective technique for component analysis and interaction analysis of biological samples such as proteins, sugars, and lipids. FTIR spectroscopy can be used to measure solid and liquid samples when applied to secondary structure analysis of proteins.


The use of an FTIR spectrometer with a highly sensitive MCT detector allows the measurement of samples with very low sample concentrations.

In order to measure a small amount of sample concentration We also used a highly sensitive, pentagonal prism multi-reflection ATR, such as the ATR Pro Penta, which is needed. This ATR has a 14-bounce, high-sensitivity ATR prism and is designed to measure low concentration samples of 0.1% or less of samples.


The measurement was performed using the spectrum (difference spectrum with water) of 0.01% lysozyme aqueous solution (Figure 5). Even at a low concentration of 0.01%, the peaks of amide I and amide II are clearly separated, and the peak shape is clear, so amide I information can be used for secondary structural analysis (Figure 6). Figure 7 shows the resulting concentration values.