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Applications

Practical Information for the Molecular Biologist

Spectrophotometric Conversions

Physical Properties of Nucleotides

Compound	Molecular weight	Max. A (pH 7.0)	Absorbance at max. 1 M solution (pH 7.0)
ATP	507.2	259	15,400
CTP	483.2	271	9,000
GTP	523.2	253	13,700
UTP	484.2	262	10,000
dATP	491.2	259	15,200
dCTP	467.2	271	9,300
dGTP	507.2	253	13,700
dTTP	482.2	267	9,600

Biophysical Data for Deoxynucleoside Triphosphates

Component	Molecular weight (Daltons)	Molar extinction coefficient and peak absorbance wavelength (pH 7.0)
dATP	491	15,200 at 259 nm
dCTP	467	9,300 at 271 nm
dGTP	507	13,700 at 253 nm
dTTP	482	9,600 at 267 nm

Conversion to Weight (µg/ml)

Double-stranded DNA (dsDNA):
A₂₆₀ = OD₂₆₀ = 1 for a 50 µg/ml solution

Single-stranded RNA (ssRNA):
A₂₆₀ = OD₂₆₀ = 1 for a 40 µg/ml solution

Single-stranded DNA (ssDNA):
A₂₆₀ = OD₂₆₀ = 1 for a 33 µg/ml solution

Absorbance =
Molar Extinction Coefficient x Concentration x Pathlength (usually cuvette width)