September 30, 1960
Dear Alfred,
Thank you so much for sending a copy of the manuscript on amino acid incorporation.  However, when I started to go through it I realized that the many figures you refer to were not included.  Is it possible to get copies of The Figures that go with it as soon as possible.
While I am writing there were several questions I did want to ask about your paper on S-RNA.
1) At what stage in your procedure do you get rid of DNA and have you done any analyses for deoxpentose containing material in your purified preps?  We found that some of our more recent preps were contaminated with deoxyoligonucleotides and it was a real chore to get rid of them.
2) Our assay for leucine and valine acceptor activity of our most purified preps are 1.2 and 0.93 micromoles per micromole of phosphate respectively.  This is somewhat different from the values you reported.  I wondered if you have a small amount of your RNA preparations that we could test with our purified enzymes for the amount of amino acid bound.  Also, with the enzyme which links AMP and CMP to the RNA we could determine if all the ends are intact.  Without any prior degradation our preparations accept less than 5% AMP and less than 2% CMP than would be predicted if all chains were stripped of the ACC.
Writing this review is killing me and I can't wait until it's finished!
With very best regards from all here.
Sincerely,
Paul Berg