September 27, 1956

Dr. J. T. Park

Arny Medical Graduate Sohool
Walter Seed Hospital
Washington 12, D.C.

Dear Dr. Park:

I would be grateful to ypu for reprinte of your studies on accumlation
of uridine derivatives in bacteria. Marv Johnson may have told you something
of our current studies on protoplasts and L-formsa, which, I suspect may be
made to tie in wery nicely with your leading observations. I did mention
this question briefly in a note, in press in PNAS, on the fsx forsation
of protoplasts, but have thought it advisable to spell it out more clearly,
as in the enclosure which is being sent to J. Bact. If I ve overlooked
any work of yours, or anyone else's, that ought to be brought out explicitly
within the compass of a very brief contribution, I would appreciate hearing
of it.

We have almost simultaneously gotten involved in uridine derivatives
from a completely different angle: you aust know of Kalckar's recent work
on galactosemia; anyhow, we had been studying gal actose-megative mtants of
E. coli from another ahgle, and Kurahashi looked at them enzymatioally in
Kalckar's lab. Some of them lack galactokinase, others the UDP-Gal transferase
(GQal~P + UPP-Glu —~ Glu-P + UPPRoGal). So far, none of the mutants have been
blocked in the epimsrase, and we're wondering if such a defect might not have
other drastic consequences. It would be invaluable to our genetic work if |
there could be devised som crude but quick “ppot-test" or the like for the
presence/absence of some of the relevant enzymes; any suggestions wuld be
gratefully received,

Youre einoerely,
Br te

/Joubua Lederberg,
“ Professor of Gend ties