Lysozyme helical content

Helical contents are much the same as those reported for lysozyme (Robbins and Holmes, 1970 Barel et al., 1972). 

The compact core of lysozyme consists of three antiparallel ]8-structures, e.g. the section 41-48 is H—bonded to the 54—49 section, which in turn is partly H—bonded to the 58-61 section [50-52]. In myoglobin, wliich contains practically no jS-structure, rigidity is provided by its high helical content ( 80%). The helical segments are held together by occasional H—bonds (for example Tyrosine H 22 with Isolencine FG 5) or are bound to the heme group [53]. Many other examples could be given. 

A comparative study on the secondary structure of hen egg white, turtle Testudo grorea) egg white, and fruit fly Ceratitis capitata) egg lysozymes has been carried out using c.d. spectroscopy. Differences in the near-u.v. spectra of these enzymes agreed with the different contents of L-tryptophan residues. The far-u.v. c.d. spectra showed the existence of a high content of unordered structure in the insect lysozyme in comparison with the high participation of a-helical conformation in the hen egg white enzyme. Differences in the dichroic behaviour between both enzymes were also remarkable under denaturing conditions. 

---