High pressure enzymatic activity

Two enzymatic systems, i.e., calpain and cathepsin influence tenderization of meat. The activity of calpain reduces under high pressure. The activity of p-calpain is also reduced during ageing (Ouali, 1990). Qin et al. (2001) showed that high-pressure treatment (100-300 MPa, 10 min) of beef resulted in a decrease in the total calpain activity however, the acid phosphatase and alkaline phosphatase activities were not significantly reduced. Homma et al. (1995) found that the total activity of calpain in pressurized muscle increased due to a reduction in the level of calpastatin because of its pressure sensitivity this in turn resulted in meat tenderization. 

Northrop, D.B. (2002). Effects of high pressure on enzymatic activity. Biochim. Biophys. Acta. 1595, 71-79... 

Michor, H. Marr, R. Gamse, T. Enzymatic Catalysis in Supercritical Carbon Dioxide Effect of Water Activity. High Pressure Chem. Eng. 1996a, 12, 115-120. 

The bound mercury is delivered to the mercuric reductase in the cytosol, which requires intracellular NADPH and thiol as cofactor for enzymatic activity. Mercury reductase reduces toxic Hg2+ to less toxic Hg° which is volatilized out of the system due to its high vapor pressure (Ghosh, 1996). 

Apart from the direct conformational changes in enzymes, which may occur at very high pressures, pressure affects enzymatic reaction rates in SCFs in two ways. First, the reaction rate constant changes with pressure according to transition stage theory and standard thermodynamics. Theoretically, one can predict the effect of pressure on reaction rate if the reaction mechanism, the activation volumes and the compressibility factors are known. Second, the reaction rates may change with the density of SCFs because physical parameters, such... 

Carotenoid biosynthesis takes place in a membrane-bound multienzyme complex, making it difficult to isolate and purify the enzymes involved. Owing to their sensitivity to detergents and low abundance, only a few have been purified from plant tissue. Many others had to be heterologously expressed in a way that high-pressure cell breaking resulted in a soluble and enzymatically active form [18,... 

Labeling of GOx with Fc groups by reaction of its lysine residues was also performed by reductive amination with 3 [15,16]. A lower Fc loading was reached with this procedure (between 1 and 6 Fc/GOx). This loading could be increased by applying high pressure during the reaction [17]. A partial loss of enzymatic activity was observed concomitantly. 

Hence, enzyme activity is not always unwanted. On the contrary, many industrial applications of enzymatic catalysts are known, including food processing (e.g., brewing, dairy, and starch industry) and chemical and pharmaceutical industry [9, 16-20]. However, this chapter is focused on the case of high-pressure processing of foods aimed at the prolongation of shelf life. Hence, the emphasis is placed on the inactivation of enzymes related to quality of food products. 

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