Laser raman and infrared spectrum analysis on low-density lipoproteins purified from hen egg yolk

Diversified proteins were separated from hen egg yolk by ammonium sulphate rapid fractionation, and pure low-density lipoprotein (LDL) was obtained after filtrating through Sephadex G-200 chromatography. After the qualitative detection ofSodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), we discovered that LDL consists of five major apoproteins. The results show that: (1) the CH2 presents asymmetric stretching and symmetric stretching mode, (2) thederivative of cholesterol C=C stretching vibration is at 1652.07 cm-1 in the Raman spectrum, and (3) a-helix bands in apolipoprotein is at 1655.12 cm-1 in the infrared spectrum. The results also suggest that laser raman and infrared spectrum analysis on LDL can provide useful information for studying the LDL structure. Key words: Low-density lipoprotein (LDL), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), C-H stretching vibration, infrared spectrum, laser raman spectrum.