Enzymes thermal stress

Stability of an enzyme is usually understood to mean temperature stability, although inhibitors, oxygen, an unsuitable pH value, or other factors such as mechanical stress or shear can decisively influence stability (Chapter 17). The thermal stability of a protein, often employed in protein biochemistry, is characterized by the melting temperature Tm, the temperature at which a protein in equilibrium between native (N) and unfolded (U) species, N U, is half unfolded (Chapter 17, Section 17.2). The melting temperature of a protein is influenced on one hand by its amino acid sequence and the number of disulfide bridges and salt pairs, and on the other hand by solvent, added salt type, and added salt concentration. Protein structural stability was found to correlate also with the Hofmeister series (Chapter 3, Section 3.4 Hofmeister, 1888 von Hippel, 1964 Kaushik, 1999) [Eq. (2.18)]. 

Loss of catalytic capacity during reactor operation is a major concern for enzyme catalyzed reactions. Such loss can be produced by different reasons like shear stress (Joshi et al. 2001), surface tension (Sarkar et al. 1987), matrix attrition and desorption in the case of supported enzymes (Regan et al. 1974), but thermal inactivation is by all means the most relevant (Peterson et al. 1989 Turner and Vulfson... 

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