TY - JOUR T1 - Conformational and functional transitions in class II alpha-mannosidase from aspergillus fischeri JF - Journal of Fluorescence Y1 - 2010 A1 - Shashidhara, K. S. A1 - Gaikwad, Sushama M. KW - Aggregation KW - alpha-Mannosidase KW - ANS binding KW - Circular dichroism KW - fluorescence KW - GdnHCl KW - Hydrobicity KW - Thermal denaturation AB -

The conformational transitions in an oligomeric and high molecular weight class II alpha-mannosidase from Aspergillus fischeri were examined using fluorescence and CD spectroscopy under chemical, thermal and acid denaturing conditions. The enzyme lost the activity first and then the overall folded conformation and secondary structure. The midpoint values of GdnHCl mediated changes measured by inactivation; fluorescence and negative ellipticity were 0.48 M, 1.5 M and 1.9 M, respectively. The protein almost completely unfolded in 4.0 M GdnHCl but not at 90 A degrees C. The inactivation and unfolding were irreversible. At pH 2.0, the protein exhibited molten-globule like intermediate with rearranged secondary and tertiary structures and exposed hydrophobic amino acids on the surface. This species showed increased accessibility of Trp to the quenchers and got denatured with GdnHCl in a different manner. The insoluble aggregates of a thermally denatured protein could be detected only in the presence of 0.25-0.75 M GdnHCl.

PB - SPRINGER/PLENUM PUBLISHERS CY - 233 SPRING ST, NEW YORK, NY 10013 USA VL - 20 IS - 4 U3 - Foreign U4 - 1.966 ER -