TRANSCRILED FROM RECORD RECEIVED 3/3/58 FROM DR, LEDERBERG

Madison, Wisconsin
February 26, 1958

Dr. Joseph Lein
Bristol Laboratories Inc.
Syracuse 1, New York

Dear Joer

I showld have given you another month's respite, but by the
time you dig through the pile on your desk to get to this,
it may be then after all,

In another connection, I got to wonder about the substitution
of silicon for carbon and it occurred to me that I had seen
nothing at all on the biological activity of analogues of
this sort. Under normal circumstances, it would,of course,
be very difficult for a silicate to enter into the chain of
carbon metabolism, However, I would suspect that classes

of compounds like those I have more conveniently written
out on the attached sheet would be quite apt and that
information as to whether these function as substitutes or
as strong: antagonists for the indicated compounds might be
useful, At any rate, this is a departure in the development
of chemotherapeutic analogues that would be worth at least
searching through the literature for?

Gould I ask to have found out what there is to say about
this? I have in mind first of all the availability of this
class of materials as chemical products, and second, whether
any biological tests of any sort have been done with them.
In some cases, they would be equally interesting whether
substrates or antagonists.

For practical application, I had in mind usin, the same
principles of choice of differential compounds as we have
discussed before,

With all best regards,

Yours sincerely,

Joshua Lederberg

JLiac