February 15, 1950

Dr. John P. Hollis,
Department of Botany,
University of Missourl,
Célutbia, issouri.
Dear Dr. Hollis:
Our "alkali-hydrolysed" yeast nucleic acid is prepared as follows
(according to Levene):

Dissolve log. "Yeast Nucleic Acid" (Sclmzarz Co.) in 90 mi H,0 + 16 al

2
conc. NH, OH. Place in Mason Jar cr other stoppered vessel, and autoclave
at 15 lbs. pressure for 66 ~ 120 minutes. The product can be conveniently
neutralized by bubbling CO,. It supposedly contains mixtures of free purine
bashs, nucleosides and some nucleotides, and has generally been satisfactory
if not used in too high a concentration. Probably it would be better to
distill most of the amaondia cff before noutralizéng it. I have of ten
diluted the hydrolysed material with an equal part of unhydrolysed
sodiun "ribonucleate" to help assure that more complex compounds will
also be represented in the mixture.

Sincerely,

Joshua Lederberg,
Assistant Professor of Genetics