An Improved Method for the Isolation of Highly Polymerized Native Deoxyribonucleic Acid from Certain Protozoa*

This is the authors' abstract. We don't add key points for this paper.

SYNOPSIS A relatively simple phenol extraction method, with EDTA as the nuclease inhibitor, is described for the isolation of purified, highly polymerized native DNA from Trichomonas vaginalis, Trichomonas gallinae, and Tritrichomonas foetus; it is applicable also to Tetrahymena pyriformis. RNase Tl, RNase A (Worthington's R), pronase, and α‐amylase digestions constitute important steps in obtaining satisfactory yields of DNA. High degree of polymerization of the isolation product was estimated by hyperchromicity at O.D.260 after DNase treatment and by CsCl gradient analysis. The double‐stranded condition of the DNA samples was estimated by the latter method and by denaturation with NaOH, and the molecular weight by sucrose gradient analysis. Purity of the samples was determined spectrophotometrically and by chemical analyses for protein and glycogen. DNA percent recovery was estimated by the diphenylamine reaction.