Limitation of DNA-4',6-diamidine-2-phenylindole assay in the presence of an excess of tRNA.
4',6-Diamidino-2-phenylindole, DAPI, forms fluorescent complexes with DNA. This property has been used to quantify DNA on the basis of fluorometric test. However, the fluorescence quantum yield of DAPI increases also with tRNA. DNA estimation needs particular care in the presence of tRNA. For DNA containing 50% adenine-thymine (AT), DAPI can be used if DNA represents at least 3.4% of the total nucleotide material. This percentage varies with the AT/guanosine-cytosine content. When the fraction of DNA decreases further, the DAPI assay can no longer be used.
Katouzian-Safadi
M
M
Centre de Biophysique Moléculaire, CNRS, Orleans, France.
Cremet
J Y
JY
Charlier
M
M
D004269:DNA, Bacterial / Q000032:analysis*; D004926:Escherichia coli; D005453:Fluorescence; D007211:Indoles / Q000032:analysis*; D012343:RNA, Transfer / Q000032:analysis*
D004269:DNA, Bacterial; D007211:Indoles; C007293:DAPI; D012343:RNA, Transfer