FIELD: chemistry.
SUBSTANCE: invention relates to biotechnology and provides a DNAase or an enzymatically active fragment thereof, the method for removing a contaminating nucleic acid from reverse transcription reaction mixtures, nucleic acids encoding the said DNAase and kits or compositions comprising the said DNAase. The DNAase having the sequence of SEQ ID NO: 1, or an enzymatically active fragment SEQ ID NO: 1, or a sequence which is at least 95% identical thereto, but wherein the proline residue at position 237 of SEQ ID NO: 1 or the equivalent proline in other sequences, has been modified, deleted or substituted, the said DNase or the enzymatically active fragment thereof being substantially irreversibly inactivated by heating at a temperature of about 50°C for 5 min. in a buffer solution comprising 25 mM Tris/HCl, pH 8.5, 5 mM MgCl2 and 1 mM DTT, and which is substantially specific for the double-stranded DNA.
EFFECT: invention provides a method for the removal of the contaminating DNA from reverse transcription reaction mixtures, hot-start DNA polymerase preparations and hot-start PCR reaction mixtures.
35 cl, 19 dwg, 9 ex
