Double-stranded specific DNase produced by Escherichia coli upon lambda bacteriophage infection that digests one DNA strand starting from 5’ terminus.
Description:
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Double-stranded specific DNase that requires the presence of a 5'-phosphate group for activity.
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PCR products prepared using one PCR primer phosphorylated at the 5'-end and the other primer unphosphorylated can be treated with lambda exonuclease to yield a single-stranded DNA.That helps to obtain a clean readable sequence without the extraneous bands which are often present when PCR products are sequenced directly.
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DNA digestion with lambda exonuclease is especially helpful when sequencing PCR products with a high GC content.
Unit Definition: One unit produces 10 nmoles of acid-soluble deoxribonucleotide from double-stranded DNA in 30 min at 37°C.
Storage Conditions: Store at –20°C.
For unambiguous PCR Sequencing:
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digest purified DNA with Recombinant Lambda Exonuclease
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heat to inactivate enzyme
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ready for DNA sequencing
Assay Conditions: 67 mM glycine-KOH (pH 9.4), 50 µg/ml bovine serum albumin, 2.5 mM MgCl2, 20 µg/ml sonicated [³H]-labeled lambda DNA and lambda exonuclease in 50 µl for 30 min at 37°C.
Quality Control: All preparations are assayed for contaminating nonspecific endodeoxyribonuclease and 3' exodeoxyribonuclease activities. Tested for the presence of linear DNA.
References:
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Little, John W. (1981)Gene Amplification and Analysis 2, 135-145.