... 2003 A single amino acid substitution of Leu130Ile in snake DNases I contributes to the acquisition of thermal stability A clue to the molecular evolutionary mechanism from cold-blooded to warm-blooded ... DNases I. AmphibianDNasesIhaveaSer205insertioninaCa2+-binding site of mammalian and avian enzymes that reduces their thermal stabilities [Takeshita, H., Yasuda, T., Iida, R., Nakajima, T.,Mori, ... byinsertion of a Ser residue into the Ca2+-binding site,resulting in thermal instability compared with DNases I from mammals and birds [14]. Fish DNase I alsoexhibited similar low thermal stability...