A thermostable enzyme having polymerase activity and substantially no nuclease activity is provided. The thermostable enzyme is characterized by comprising a sequence of nine amino acid residues at least proximal to the N-terminus that has less than 50% but greater than 40% amino acid sequence identity with residues 280 to 288 of the naturally occurring Thermus aquaticus polymerase. The subject enzyme finds use in a variety of different application in which polynucleotides are enzymatically produced, particularly in PCR based applications.