Volume Change of the Random Coil to Folded Conformational Transition of <i>Thermomyces</i><i>lanuginosus</i>Xylanase at 24&#176C and pH = 7.0 via Application of the Clausius-Clapeyron Equation  

作　　者：Heather N. H. Wilks Tara M. Arrington Billy Mark Britt 

机构地区：[1]Department of Chemistry and Biochemistry, Texas Woman’s University, Denton, Texas, USA

出　　处：《Journal of Biophysical Chemistry》2014年第4期134-142,共9页生物物理化学（英文）

摘　　要：A partial phase diagram characterizing the conformational change that occurs in Thermomyces lanuginosus xylanase as it is slowly heated in 150 mM sodium phosphate (pH = 7.0) has been con-structed from slow-scan-rate differential scanning calorimetry measurements. The Clausius-Clapeyron equation was applied to determine an associated volume change of -205 L·mol-1 at 24°C, the equilibrium transition temperature at 1.0 atm pressure. This value is in excellent agreement with that predicted using a previously published [1] empirical equation for calculating the hydro-dynamic radius if the transition is regarded as from a random coil to a functional, folded state and with the assumption that the hydrodynamic radius is a good approximation of the true random coil radius. The existence of a low-temperature random coil is confirmed by circular dichroism and dynamic light scattering measurements. Thus, at 24°C and 1.0 atm pressure the enzyme appears to fold from a random coil to a functional, folded form as it is slowly heated.A partial phase diagram characterizing the conformational change that occurs in Thermomyces lanuginosus xylanase as it is slowly heated in 150 mM sodium phosphate (pH = 7.0) has been con-structed from slow-scan-rate differential scanning calorimetry measurements. The Clausius-Clapeyron equation was applied to determine an associated volume change of -205 L·mol-1 at 24°C, the equilibrium transition temperature at 1.0 atm pressure. This value is in excellent agreement with that predicted using a previously published [1] empirical equation for calculating the hydro-dynamic radius if the transition is regarded as from a random coil to a functional, folded state and with the assumption that the hydrodynamic radius is a good approximation of the true random coil radius. The existence of a low-temperature random coil is confirmed by circular dichroism and dynamic light scattering measurements. Thus, at 24°C and 1.0 atm pressure the enzyme appears to fold from a random coil to a functional, folded form as it is slowly heated.

关 键 词：Clausius-Clapeyron Conformational CHANGE Slow-Scan-Rate Differential Scanning Calorimetry THERMOMYCES LANUGINOSUS XYLANASE Volume CHANGE 

分 类 号：O6[理学—化学]