Studies on the synthesis of estrogen-specific uterine proteins. Comparison of methods of quantitative evaluation of double-isotope peaks.
Double-isotope techniques are frequently used to provide a sensitive means of detecting specific biosynthetic responses to experimental manipulations, usually protein or nucleic acid synthesis. The qualtative basis for the detection of changes in biosynthetic rates in these double-isotope experiments involves measuring changes in the ratio of the isotopes to each other after fractionation of the albeled extract. Changes in the isotope ratios have been used directly in quantitative interpretations also, but such quantitative interpretations of changes in isotope ratios are potentially erroneous since the magnitude of the change in ratio of one isotope to the other will depend upon the total number of counts within the area in question (the 'baseline'). The results of experiments on an estrogen-specific uterine protein are presented in this report. It is demonstrated that under conditions in which the 'baseline' incorporation of isotope varies within an experiment, such as in purification or pulse-chase studies, the use of isotope ratios to quantify the data results in erroneous values. In these instances computations using the delta 14C method described by Mayol and Sinsheimer (1970) provides for what appear to be valid conclusions. However, under conditions in which the baseline incorporation of isotope of the control and experimental groups does not vary, as in studies of the temporal course of synthesis and dose-response relationships, the use of increases in isotope ratios is adequate for quantitative interpretations.
D000818:Animals; D002250:Carbon Radioisotopes; D004305:Dose-Response Relationship, Drug; D004589:Electrophoresis, Disc; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007553:Isotope Labeling; D007930:Leucine / Q000378:metabolism; D008433:Mathematics; D008722:Methods; D014176:Protein Biosynthesis; D051381:Rats; D012967:Sodium Dodecyl Sulfate; D013997:Time Factors; D014316:Tritium; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
D002250:Carbon Radioisotopes; D014316:Tritium; D012967:Sodium Dodecyl Sulfate; D004958:Estradiol; D007930:Leucine