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Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III. January 1944.

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Title:	Studies on the Chemical Nature of the Substance [9 of 23]
Alternative Title:	Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III
Creator:	Avery, Oswald T.
Contributor:	MacLeod, Colin M.
Publisher:	Journal of Experimental Medicine
Date:	1944-01-00
Subject:	Cellular signal transduction
Description:	From the Journal of Experimental Medicine Vol. 79, No. 1.
Type:	Text
Format:	text/plain
Language:	en
Identifier:	avery-pg09.jpg
Source:	Master scanned with Epson GT-10000+ flatbed scanner at 600 dpi.
Rights:	http://osulibrary.orst.edu/specialcollections/coll/pauling/dna/copyright.html
Full Text:	OSWALD T. AVERY, COLIN M. MACLEOD, AND MACLYN MCCARTY‘45 for desoxyribonucleic acid is strongly positive. The orcinol test (Bial) for ribonucleic acid is weakly positive. However, it has been found that in similar concentrations pure preparations of desoxyribonucleic acid of animal origin prepared by different methods give a Bial reaction of corresponding intensity. Although no specific tests for the presence of lipid in the purified material have been made, it has been found that crude material can be repeatedly ex- tracted with alcohol and ether at -12°C. without loss of activity. In addition, as will be noted in the preparative procedures, repeated alcohol precipitation and treatment with chloroform result in no decrease in biological activity. Elementary Chemical Analysis.'-Four purified preparations were analyzed for content of nitrogen, phosphorus, carbon, and hydrogen.­he results are presented in Table I.­he nitrogen-phosphorus ratios vary from 1.58 to 1.75 with an average value of 1.67 which is in close agreement with that calculated TABLE I Elementary Chemical Analysis of Purified Preparations of the Transforming Substanre Preparation No.œarbon¡ydrogen§itrogen©hosphorus§IP ratio per cent©er tend©er cent©er tend 37“4.27“.89‘4.21˜.57‘.66 38B…2d…2d‘5.93™.09‘.75 42“5.50“.76‘5.36™.04‘.69 44…2d…2d‘3.40˜.45‘.58 Theory for sodium desoxyribonucleate.....“4.20“.21‘5.32™.05‘.69 on the basis of the theoretical structure of sodium desoxyribonucleate (tetra- nucleotide). The analytical figures by themselves do not establish that the substance isolated is a pure chemical entity. However, on the basis of the nitrogen-phosphorus ratio, it would appear that little protein or other sub- stances containing nitrogen or phosphorus are present as impurities since if they were this ratio would be considerably altered. Enzymatic Analysis.-Various crude and crystalline enzymes have been tested for their capacity to destroy the biological activity of potent bacterial extracts. Extracts buffered at the optimal pH, to which were added crystalline trypsin and chymotrypsin or combinations of both, suffered no loss in activity following treatment with these enzymes.©epsin could not be tested because ' The elementary chemical analyses were made by Dr. A. Elek of The Rockefeller Institute. ' The authors are indebted to Dr. John H. Northrop and Dr. M. Kunitz of The Rockefeller Institute for Medical Research, Princeton, N. J., for the samples of crystalline trypsin, chymotrypsin, and ribonuclease used in this work.