Studies on the Conjugation of Streptococcal Nucleoprotein*

Recent observations on conjugated proteins (l-6) raise the question as to whether the prevailing ideas concerning the nature of the attachment of nucleic acids with the proteins are valid. With certain exceptions it has generally been assumed that the nucleoproteins are salts of a polyvalent nucleic acid and a polyvalent base (protein) (7). The ideas that nucleoproteins are salt-like (polar), or dissociable combinations, are largely derived from results of experiments in which vigorcpus chemical methods have been used. In general the following methods have been employed: (a) extraction of cells and organs by a dilute alkaline solution, and the precipitation of the nucleoproteins with acid (8) ; (b) treatment of the starting material with acetone, or alcohol and ether; the dry material then extracted with water, saline, buffer, or alkali, and the nucleoprotein precipitated with acid (9, 10); (c) extraction of the acetoneand ether-dried material with 10 per cent saline at 70-80” for several days and the nucleoprotein precipitated with acid (11). The idea of “salt-like” combination has received further emphasis from the fact that the nucleoproteins prepared as above, and the artificial “nucleoproteins” (protein nucleates) precipitated from a mixture of nucleic acids and proteins, at times have comparable analytical results and show similar properties (7, 12, 13). This misconception is easily explainable if we consider that many so called nucleoprotein preparations are protein nucleates, or are mixtures of nucleic acids and proteins due to the splitting of the