Hlutverk sameinda-sveigjanleika í hitastigsaðlögun subtilisín-líkra serín próteinasa

摘要: The main difference between enzymes from organisms which have adapted to a different temperature, is that psychrophilic usually higher catalytic efficiency compared mesoand thermophilic enzymes. Psychrophilic also diminished thermal stability. Both of these characteristics been linked increased structural flexibility. In this research comparisons are made subtilisin-like serine proteinases temperatures, proteinase Vibriospecies (VPR) and homologous enzyme, aqualysin I the thermophile Thermus aquaticus YT-1 (AQUI). project it was attempted shed light on role flexibility in temperature adaptation. It has previously reported proline residues surface loop near N-terminal AQUI, not present VPR, involved stabilization enzyme. This prompted us investigate effect inserting VPR∆C. mutant showed heat stability as well shifting Nterminal by two amino acid residues, similar AQUI. These changes may implications for adaptation enzyme reducing protein. molecular (on millisecond scale) estimated with fluorescent quenching measurements. For approach, mutation AQUI (Y191W), gave same number Trp VPR∆C, at identical sites emission cold were quenched degree, suggesting more flexible structure VPR∆C than Y191W. Attempts estimate compare local nanosecond selected done use site-directed spin labeling electron paramagnetic resonance (EPR) spectroscopy. insert Cys-residues directed mutagenesis. proved difficult labels mutants, methods still under development. Spin EPR measurements one sites, S123C A123C will be discussed.