Colorimetric method for estimating polylysine and polyarginine

✍ Scribed by Ruth F. Itzhaki

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 341 KB
• Volume: 50
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(72)90067-x

✦ Synopsis

In the course of studies aimed at determining the percentage of free DNA-phosphate groups in chromatin (1,2) by their binding to polylysine (PL), a method was developed for estimating excess unbound lysyl residues. The method was found to be usable also for polyarginine. It involves reaction of the anionic dye methyl orange (MeO) with the lysyl or arginyl residues under conditions such that the complex precipitates: the unbound Me0 is then estimated from the absorbance of the supernatant. This procedure was adapted from a study by Wetlaufer and Stahmann (3) of the interaction of Me0 and PL.

'These compounds will be referred to subsequently as PL, polyarginine, etc., i.e., omitting HBr or HCI. Also, all concentrations will be given in terms of molarity of lysyl or arginal residues. 569