CALIFORNIA INSTITUTE OF TECHNOLOGY
PASADENA

DIVISION OF BIOLOGY
KERCKHOFF LABORATORIES OF BIOLOGY

May 17, 1955

Dr. Joshua Lederberg
Department of Genetics

The University of Wisconsin
Madison 6, Wisconsin

Dear Dr. Lederberg:

IT am sending you a sample of ONPG made by California
Research Foundation, who yielded to my repeated requests to
make the compound available commercially. Many thanks for
the sample you sent me.

Enclosed is a report on some of our work on adaptive
enzymes. The details of the scheme have changed, but the
basic view is the same, i.e., that the substrate is not
necessary for the synthesis but rather for activation or
stabilization of the enzyme and that this can occur after
synthesis. We believe that we now have a definitevexperi -
ment with the 8 galactosidase system where activation equal
to 50% of lactose induced cells can be obtained in the
presence of chloromycetin which precludes any effect of
the inducer on the synthetic mechanism.

Sincerely,

Enel.