ISSN:
1432-1017
Keywords:
Proteolipid apoprotein structure
;
sonication
;
non-denaturing detergent
;
freeze-fracture electron microscopy
;
infrared spectra
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract The conformation of brain proteolipid apoprotein (PLA) has been investigated using infrared spectroscopy and freeze-fracture electron microscopy. For this purpose, spectroscopic samples consisting of a mixture of liquid paraffin and wet protein have been prepared. These systems have allowed us to record the infrared spectra of PLA at neutral pH. The amide I and III regions reveal the existence of a predominantly α-helical structure, as well as the presence of minor β-strands and random coil forms. The effect of sonication and a non-denaturing detergent, (n-octyl-β-d-glucopyranoside), on the structure of the protein have also been investigated. Sonication produces an increase of the β and unordered structures at the expense of the α-helical conformation. These structural changes are enhanced in the presence of the non-ionic detergent n-octyl-β-d-glucopyranoside. Lipids protect the native protein structure from the effects of sonication. The aforementioned detergent changes the PLA conformation by increasing the α-helical content at the expense of β-sheet and random coil forms. Therefore the PLA structure seems to be similar to the structures of other proteins intrinsic to non-neural membranes. The effects investigated also suggest that PLA behaves in a conformationally flexible manner.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00261902
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