Application of Fourier Transform Raman Spectroscopy to Biomembranes: 1064 nm Excited Raman Spectra of Hog Kidney Mitochondria) Outer Membranes

摘要

Fourier transform Raman spectra with 1064 nm excitation were measured at ambient temperature on hog kidney mitochondrial outer membrane preparations of ultracentrifuged pellet and almost fluorescence-free Raman spectra with satisfactory signal-to-noise ratios were obtained. Fourier transform IR spectra were also measured. The observed Raman and infrared wavenumbers were tentatively assigned to membrane proteins and phospholipids, respectively. CH stretching, phospholipid CC stretching and PO_2~- stretching vibrations are discussed. To examine the applicability of near-infrared excited Fourier transform Raman spectroscopy to the study of the inhibitory effects of inorganic ions on membrane-bound monoamine oxidase activity, measurements were also made on membrane preparations suspended in phosphate buffer (pH 7.0) at ambient temperature in the absence (control) and presence of NaCl, and studies were made of phospholipid CC stretching and PO_2~- stretching vibrations, which are relatively unaffected by H_2O self-absorption by near-infrared radiation. It was found that the presence of NaCl decreased the intensity of the 1080 cm~(-1) gauche form acyl chain CC stretching Raman band relative to those of the all-trans CC stretching Raman band at 1126 and 1068 cm~(-1). This result was different from that obtained with aqueous dispersions of phosphatidylcholine (PC), for which it has been reported previously that monovalent ions such as Na~+ do not affect the I_(trans)/I_(gauche) ratio.