... responsible for stability, and in fact Ala7, Met13, and Tyr43 in HT c-552have been shown, by mutagenesis and 3D structureanalyses, to be determinants of the higher stability of HT c-552 (see below). For ... in the wild-type PA c-551 and itsquintuple mutant. The mutated residues in the quintuple mutant, and the corresponding ones of the wild-type PA c-551 and HT c-552 are coloredpurple, green, and ... purified and handled more easilythan their mesophilic counterparts. Although thermophilicFig. 4. Thermal stability of wild-type PA c-551, the quintuple mutant, and HT c-552. The heat capacity curves...