Protection of a restriction enzyme from heat inactivation by [alpha]-crystallin.

ABSTRACT

PURPOSE: To determine whether the chaperone activity of human alpha-crystallin can protect a restriction enzyme from heat inactivation. METHODS: The restriction enzyme Nde I was heated in the presence or absence of purified bovine alpha-crystallin. Following heat treatment, the enzymatic activity of the heat treated samples was assayed by cleavage of plasmid DNA. The extent of digestion was monitored by agarose gel electrophoresis and visualization of DNA fragments by ethidium bromide staining. RESULTS: Heating of Nde I in the absence of alpha-crystallin resulted in inactivation. However, Nde I heated in the presence of alpha-crystallin remained active. Furthermore, an increased amount of alpha-crystallin provided a longer period of thermal protection. CONCLUSIONS: The chaperone activity and thermo-protective effect of alpha-crystallin extend to protection of enzymatic activity, not merely the protection from thermally induced aggregation/denaturation. In addition, inclusion of alpha-crystallin during some enzymatic reactions may be beneficial.