Oligonucleotide labeling buffer

1 mg/ml random deoxynucleotide primers, six bases in length

1 M HEPES (adjusted to pH 6.6 with 4 N NaOH)

20 mM dithiothreitol

250 mM Tris-Cl (pH 8.0)

25 mM MgCl₂

2 mM each of the unlabeled dNTPs

Store the 5x buffer in small aliquots at -20°C. The buffer may be frozen and thawed several times without harm.

The composition of the 5x oligonucleotide labeling buffer depends on the [α-³²P]dNTP to be used. If radiolabeled dATP is to be used, the buffer should contain dCTP, dTTP, and dGTP. If two radiolabeled dNTPs are used, the buffer should contain two unlabeled dNTPs.