Enzymes from high-temperature microorganisms

Extremozymes: expanding the limits of biocatalysis

The study of enzymes isolated from organisms inhabiting unconventional ecosystems has led to the realization that biocatalysis need not be constrained to mild conditions and can be considered at pH's, temperatures, pressures, ionic and solvent environments long thought to be destructive to biomolecules. Parallel to this, it has been demonstrated that even conventional enzymes will catalyze reactions in solvents other than water. However, the intrinsic basis for biological function under extreme conditions is only starting to be addressed, as are associated applications. This was the focus of a recent NSF/NIST-sponsored workshop on extremozymes. Given the information acquired from the study of extremozymes, modification of enzymes to improve their ranges of stability and activity remains a possibility. Ultimately, by expanding the range of conditions suitable for enzyme function, new opportunities to use biocatalysis will be created.

Thermostability and thermoactivity of enzymes from hyperthermophilic Archaea

Enzymes from hyperthermophilic microorganisms are characteristically thermostable and thermoactive at extremely high temperatures. Information about the basis for the structure and function of these novel proteins is beginning to emerge. However, there are very few generalizations that can be drawn at this point that can be derived from the limited number of studies that have focused on biocatalysis and thermostability at extremely high temperatures.

Protein engineering for unusual environments

The ability to use proteins in unusual or non-natural environments greatly expands their potential applications in biotechnology. Because natural selection has neither maximized the stability of proteins nor optimized them to function under unusual conditions, there is considerable room for their improvement by protein engineering. Significant advances reported within the past year include a dramatic demonstration of a protein's ability to tolerate changes in its amino acid sequence, large increases in protein stability, and the use of random mutagenesis to obtain novel enzymatic properties. Approaches using random or site-directed mutagenesis have been successful in generating proteins able to function in an extended range of environments.