This thesis describes the use of (FT-)IR spectroscopy in general biochemical research. In chapter 3, IR spectroscopy is used in the quantitation of residual detergent after reconstitution of an integral membrane protein in a pre-defined lipid matrix. This chapter discusses the choice of the vibrational band for quantitation. Calibration is performed by ratioing the peak height of a detergent signal against the peak height of a phospholipid signal. The use of IR spectroscopy is compared to other quantitative analytical methods. In the past few years, FT-IR spectroscopy has become very popular to study the secondary structure of proteins. Chapter 4 describes the first detailed study on the secondary structure of the photoreceptor, rhodopsin. It is concluded that the C-terminal region of rhodopsin adopts a beta-sheet structure and that the third cytoplasmic loop is formed by an alpha-helix. In chapter 5, a study on interactions occurring between Na+,K+-ATPase and phospholipids with increasing unsaturated acyl chains is presented. Na+,K+-ATPase disturbs the lipid order in relatively saturated phospholipid membranes. Incorporating the protein in a highly unsaturated lipid matrix at low temperature results in no apparent hydrophobic interaction. From the changes in the amide I band it is concluded that protein aggregation has occurred. By increasing the temperature however, aggregation is diminished, thereby increasing the possibility for hydrophobic interaction between the protein and phospholipid. Finally, chapter 6 deals with an analysis of the formation of succinimide derivatives in small peptide fragments. Formation of such derivatives provides a mechanism for the age-dependent degradation of proteins in vivo, since for example, some breakdown products of alpha A-crystallin, found in the ageing eye lens,can be the result of hydrolysis of a succinimide

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Promotores : J. de Pont en W. de Grip

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