ISSN:
1573-5001
Keywords:
Pichia farinosa
;
protein unfolding
;
pulsed-gradient spin-echo
;
salt-mediated killer toxin
;
translational self-diffusion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The solution behaviour with respect to pH and NaCl concentration of the tertiary structure and propensity for aggregation of salt- mediated killer toxin (SMKT) from Pichia farinosa was examined using pulsed-gradient spin-echo NMR diffusion measurements. It was found that in 0.15m NaCl the tertiary structure of SMKT was constant below pH 5.0, with the native SMKT existing as an unaggregated heterodimer containing the β-subunit in a compactly folded form. However, above pH 5.0 the β-subunit dissociated and lost its compact structure, becoming a random coil with an ∼37% increase in effective hydrodynamic radius. To determine the effects of NaCl concentration on the tertiary structure of SMKT, diffusion measurements were performed at pH 3.5 and NaCl concentrations up to 2M. Both the tertiary structure and aggregation state of SMKT were found to be insensitive to the salt concentration which indicates that the activity of the toxin is not a direct result of salt–protein interactions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008394716710
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