Sub-zero temperature inactivation of carboxypeptidase Y under high hydrostatic pressure.

摘要: High hydrostatic pressure induced cold inactivation of carboxypeptidase Y. Carboxypeptidase Y was fully active when exposed to subzero temperature at 0.1 MPa; however, the enzyme became inactive high and were both applied. When treated pressures higher than 300 MPa temperatures lower −5 °C, it underwent an irreversible in which nearly 50% α-helical structure lost as judged by circular dichroism spectral analysis. applied limited below 200 MPa, process appeared be reversible. In thepresence reducing agent, this reversible phenomenon, observed diminished give enzyme; agent reduces some disulfide bridge(s) area that is newly because inactivation. Such unavailable if carboxypeptidase Y its native conformation. Because all bridges locate near site cleft, suggested structural destruction, any, occurs preferentially rich area. A possible mechanism pressure-dependent CPY destroy α-helix region, creates hydrophobic environment. This destruction probably a result reallocation water molecules. Experiments carried out presence denaturing agents (SDS, urea, GdnHCl), salts, glycerol, sucrose led conclusion consistent with idea reallocation.