COMPARISON OF PROTEIN SECONDARY STRUCTURE CALCULATION METHODS BASED ON INFRARED SPECTRA DECONVOLUTION 

Subject of Research. The paper presents comparison of two different spectroscopic methods for the quantitative determination of the secondary structure components of two globular proteins with different secondary structure, such as human serum albumin and porcine trypsin. The variability and reproducibility of each method are analyzed. Method. The secondary structure of proteins was determined by two common spectroscopic methods for quantitative assessment of protein secondary structure, such as deconvolution of amide I absorption band in the infrared spectrum and deconvolution of infrared spectrum second derivative in the frequency range of amide I. We used spectra after subtraction of the solvent spectrum from the protein solution spectrum for these methods. Main Results. Comparison of two spectroscopic methods shows that the second derivative deconvolution method for protein infrared spectrum provides greater reproducibility of the secondary structure components in independent experiments compared to the decomposition of the spectrum in the amide I absorption band for both albumin and trypsin. The coefficient of variation in the second derivative deconvolution also has a small value, therefore, the method of the second derivative gives a more accurate determination of the protein secondary structure as opposed to the contour decomposition of amide I band. The obtained results of the second derivative deconvolution are in better agreement with computational methods and X-ray analysis. Practical Relevance. Experimental results obtained by comparison of different methods of secondary structure quantitative determination for proteins allow choosing the most accurate calculation method, which can provide information on the structural stability and dynamics of protein in various media and assess the content of protein secondary structures.

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