Secondary structure of the entomocidal toxin from Bacillus thuringiensis subsp. kurstaki HD-73.
The secondary structure of the toxin from Bacillus thuringiensis subsp. kurstaki (Btk) HD-73 was estimated by Raman, infrared, and circular dichroism spectroscopy, and by predictive methods. Circular dichroism and infrared spectroscopy gave an estimate of 33-40% alpha-helix, whereas Raman and predictive methods gave approximately 20%. Raman and circular dichroism spectra, as well as predictive methods, indicated that the toxin contains 32-40% beta-sheet structure, whereas infrared spectroscopy gave a slightly lower estimate. Thus, all of these approaches are in agreement that the native conformation of Btk HD-73 toxin is highly folded and contains considerable amounts of both alpha-helical and beta-sheet structures. No significant differences were detected in the secondary structure of the toxin either in solution or as a hydrated pellet.
Choma
C T
CT
Department of Chemistry, University of Ottawa, Ontario, Canada.
Surewicz
W K
WK
Carey
P R
PR
Pozsgay
M
M
Kaplan
H
H
D001413:Bacillus thuringiensis; D001427:Bacterial Toxins; D002942:Circular Dichroism; D011487:Protein Conformation; D011498:Protein Precursors; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
C029103:Bacillus thuringiensis protoxin; D001427:Bacterial Toxins; D011498:Protein Precursors