Chemical Nature and Biolosrical Specificity of the Substance Inducing

        Transformation of Ynsumococcal Tvpea

ABYTMCT

Maclyn McCarty
Lt.Lmdr. (MC) thiln

The specific substance reeponsible for the induction of transforma-

tion of pneumococcal types has been isolated from three seFate types of
Pneumococcus in the form of desoxyribonucleic acid fractions. Chemical,
pbsico-chemical and serological analysis of the purified m&terial rrupport
ths view that biological activity is a property of the desoxyribonucleic

Eicid *  Further evidenoe on this point has been obtained by the application

of enzymatic techniques,  The ensyme deaoxyribonuclease has been isolated

in purified form from beef pancreas and has been shown to be highly active

in attacking polymerized desoxyribonucleic acid from animal sources. In

concentrations of lees thanO&l cig. per cc. desoxyribonuclease causes com-

plete and irreveroible lose of biological activity of the transforming eub-

stance.  The enzymatic evidence is thus ccnfirmatory of the desor.yribonucleic

acid nature of the active substancr.

While the results obtained-with t3ze transforming substance indicate

that desoxyribonucleic acids Fssese biological specificity; the chemical

basis of this specificikf io not known.  The implications of the preeent

studies with respect to the problem of specificity of the nucleic acids are

discussed.

     The biological properties of the transforming substence present

an8klogies to those of viruses.  however, in the case of the pneumococcal

agent, the apparent absence of protein and the marked susceptibility to

enaymatic destruction provide significant points of difference.

From the iinited States Navy hesearch Unit at the Hospital of The iiockefsller
   Xnetitute for Yedical tiesearch


The Bureu of Medicine and Surgery of the U.S. Navy does not nece~s&

~zrily undertake to endorae the views or opinions which 6x-e exyressed

in this pqer.