Spectroscopic studies of proteins in reversed micelles

C.H.W. Vos

Research output: Thesisinternal PhD, WU


<p>The spectroscopic characterization of some protein-containing reversed micellar systems has been investigated. The concept of protein solubilization in hydrocarbon media via reversed micelles was first introduced by Gitler and Montal. Their system consisted of proteolipids, solubilized in an apolar solvent, with phospholipids as surfactant. Some years later Wells introduced the term "enzymes in reversed micelles" based on a study of phospholipase in diethylether/methanol mixtures with phosphatidylcboline as the surfactant. In this case the enzyme was already soluble in some organic solvents and the surfactant acted also as the substrate of the enzyme.<p>One of the first hydrophilic enzymes, incorporated into reversed micelles, was chymotrypsin. Detailed activity and spectroscopic data were reported by the groups of Martinek, Luisi and Menger.<p>In the following years, numerous publications, dealing with reversed micellar enzymological subjects, appeared. Three partially overlapping fields of interest can be distinguished. The first one is the study of enzymatic activity in reversed micellar solutions. Among this belongs the work done in our laboratory, which is concentrated on the optimization of biocatalytic processes in reversed micellar systems. The second field of interest consists of structural and dynamic aspects of protein containing reversed micelles. During the last few years, several groups have reported on spectroscopic and ultracentrifugation studies. The work presented in this thesis belongs to this category. The third line of interest is the study of enzyme recovery using reversed micellar systems. This type of research has gained increasing attention during the last years. It is possible to selectively extract proteins from an aqueous phase into a hydrocarbon phase containing reversed micelles and to re-extract the protein again into a second aqueous phase. This process can be applied to the purification of proteins.<p>In Chapter 2 a review is presented about spectroscopic studies performed with reversed micellar systems. In this chapter a number of techniques is described, which can be used in reversed micellar research. These techniques are both applied to "empty" and protein-containing systems.<p>Chapter 3 provides a detailed description of the time-resolved fluorescence technique and analysis, that we have applied to protein- containing reversed micellar systems. Examples are given of the fluorescence properties of three well characterized proteins in a normal aqueous environment. These examples illustrate the kind of information obtainable by studying time-resolved fluorescence properties.<p>In Chapters 4,5 and 6 investigations on Protein containing reversed micellar systems are presented. Chapters 4 and 5 describe micellar systems, containing the fluorescent cytochrome c derivatives porphyrin cytochrome c or Zn-porphyrin cytochrome c. Chapter 6 reports en studies of the same micellar systems but with alcohol dehydrogenase as the guest protein instead of cytochrome c.<p>In the last chapter of this thesis (Chapter 7) a summarizing discussion of the results is presented.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Veeger, C., Promotor
  • Visser, A.J.W.G., Co-promotor, External person
Award date19 Oct 1988
Place of PublicationS.l.
Publication statusPublished - 1988


  • biochemistry
  • biotechnology
  • chemical industry
  • proteins
  • spectral analysis
  • spectroscopy


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