July 13, 1958
Dear Dr. Ochoa,
Thank you very much for sending your comments on the manuscript. I have incorporated your suggestions into a corrected manuscript and I'll send it to Canada this week.
The reproduction of the chromatogram photographs was probably not too good in the copy I sent you but the areas that you referred to are, in fact, visible on photographs of Figure 9. I will have to be careful, however, in checking the proof to be sure all the spots can be seen.
Dr. Heppel is off in British Columbia and Russ and I are busy finishing up some experiments we did with Marianne. I hope to write up a rough draft of a paper including this data and send it off to you so that you can, if you like, use some of the information in your talks later this summer. The experiments concerned exchange with GDP, the stepwise mechanism of phosphorolysis, and the effect of 3'-ended oligonucleotides on the rate of phosphorolysis of the 5'-ended ones. Surprisingly, although they inhibit the phosphorolysis of the 5'-ended, the inhibition is not very striking. It is best when the 3'-ended is a longer chain, i.e.; ApApApUp on pApApA. We have also found that poly A inhibits exchange with UDP and poly U inhibits exchange with ADP - a situation similar to the results with polymerization.
Regards to you from Russ and from Dan. We hope you and Mrs. Ochoa continue having such a pleasant trip.
Sincerely,
Maxine Singer