Effects of high pressure on bioactive proteins, microorganisms and cultured cells and its use in the medicinal field

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Raw starch is a starting material for the industrial production of glucose and ethanol. Gelatinization of raw starch high pressure, without heating, result in saving of energy. Therefore, raw starch was pressurized under hydrostatic pressures of 1,000 to 6,000 kg/cm^2 atroom temperature for 1 h and the pressure-treated starch was compared with heat-treated starch. The pressurization up to 3,000 Kg/cm^2 had little effect on raw starch, whereas the pressurization at higher pressures than 4,000 kg/cm^2 enhanced markedly the bindability and digestibility of raw starch with glucoamylases, Gluc_1 and Gluc_2 especially with Gluc_2 which scarcely binds to raw starch and is mutch less active on raw starch than Gluc_1. For example, the binding constant for Gluc_2 of the 4,000-kg/cm^2 treated starch became 1.6x10^5M^<-1>, while that of native raw starch was 8.2x10^3M^<-1>. The 5,000-6000 kg/cm^2 treated starch was digested by Gluc_1 and GluC_2 at 4.2 and 80 times higher rates, respectively, than native raw starch. Thus, the high pressure-treated starch was not distinguishable from the high temperature (75-100ﾟC)-treated starch with respect to their bindability and digestibility with the glucoamylases. However, there were some differecoes observed between their scanning electron micrographs, indicating somewhat different mechanisms for the pressure and heat denaturations of raw starch.Enzymes such as glucoamylase, hyaluronidase and H_2-proteinase were also pressurized and the results were discussed.