11] Infrared spectroscopy

Abstract

Publisher Summary This chapter discusses the way metal ion environments in metalloproteins and metalloenzymes can be studied by using infrared (IR) spectroscopy. It explains experimental techniques and methods of analysis and interpretation by using selected examples. Fourier transform (FT) IR spectroscopy is mentioned only briefly. Although both IR and Raman spectroscopies provide information about transitions between two vibrational states, there are several advantages and disadvantages unique to each. IR and Raman spectroscopy are complementary, and both spectra should be obtained whenever possible. In fact, vibrational spectra of most of the biological compounds discussed in this chapter have been studied by IR as well as Raman spectroscopy. This chapter discusses IR spectra of axial ligands (CO, NO, O 2 , CN - , and N 3 - ), which are bound to metalloproteins and metalloenzymes. IR spectra of metalloproteins and metalloenzymes themselves constitute another area that can be studied with FTIR spectroscopy, but their full potential as a probe of the structure of metal-containing biological systems has yet to be established. In this respect, there is no doubt that Raman spectroscopic techniques have proved to be much more informative. Nevertheless, several promising FTIR studies, particularly on the secondary structures of metalloproteins, have been carried out.