May 2, 1961
Dear Ted:
Thank you very much for sending me the 3' isomer of psuedo- uridylic.  This will be very useful in pushing the identification of some of the additional compounds we have encountered.  Do you know if the 2' or 3' isomers show different behavior in various chromatographic solvents?  The reason I asked is:  (a) one of our unknown compounds separates slightly from the 2' isomer you sent us previously; (b) electrophoresis and chromatography of the 2' isomer preparation in a number of systems has yielded two U. V. absorbing spots.  One of these appears to be uridylate.  Is this consistent with your information?
We are still working on the identification of various minor compounds which appear in the terminal portions of the RNA chains and I will try to keep you informed if anything breaks.
The only recent contribution to Methods in Enzymology I have made is for a paper on acetate activation.  Is this the one you want a copy of?  Fred Bergmann is supposed to have written a paper on the preparation of the amino acid acceptor enzyme so you may contact him if that's the paper you want.
With best regards.
Sincerely yours,
Paul Berg