Role of hydrodynamic shear on activity and structure of proteins.
Proteins are important products used in industry. They may be enzymes which catalyze different reactions or they may be required for their biological activities as hormones, growth factors or therapeutics. During production and recovery, proteins are subjected to fluid forces which arise due to operations such as stirring, pumping and centrifugation. The resulting hydrodynamic shear forces may cause damage to the large molecular weight proteins, resulting in denaturation and inactivation of the protein. This is a major concern as it affects the overall efficiency of protein recovery and final yield of the product. A considerable amount of research has been devoted to studying the effects of hydrodynamic shear stress on proteins, especially with respect to the enzymes. Enzymes are subjected to shear stresses during their production in fermentors, during isolation and purification steps in downstream operations and also during their use in enzyme reactors, especially if stirred reactors are employed to perform enzyme catalysed reactions. The present review discusses the effects of fluid shear stress on proteins including enzymes. A brief description on deactivation has been included in order to understand the effect of shear on the deactivation kinetics of proteins. The model systems used to subject proteins to shear and some unit operations during protein processing or use wherein they are exposed to shear stresses have also been presented. The significance of shear effects in designing bioprocesses involving shear sensitive biocatalysts as well as suggestions for future work have also been given.
Elias
C B
CB
Department of Chemical Technology, University of Bombay, Matunga, India.
Joshi
J B
JB
D011232:Chemical Precipitation; D005285:Fermentation; D005374:Filtration; D007700:Kinetics; D011487:Protein Conformation; D013314:Stress, Mechanical