28th of March, 1966.
Dear Professor Spiegelman,
Many thanks for your letter of March 24th, for the information concerning QB and the opportunity of coming to work with you.
With regard to the base ratios of QB and our phages ZlK/l and ZJ/l, they certainly look similar although ours have less U (28.3 +/- 0.3).  However of more importance from the point of relationship is the fact that ZlK/l also has neither methionine nor histidine and probably no tryptophane - the most abundant amino-acids are serine, alanine, valine and aspartic acid.
We are almost ready to write up the properties of the phage protein: papers on the RNA have been accepted and are in the press at the moment - though they won't appear in the Biochem. J. till the Autumn.  With regard to the phage protein let me list what we are intending to publish.  The extraction and amino-acid composition of ZlK/l and ZS/3 (the latter is almost identical to MS 2), the behaviour of ZlK/l protein on Sephadex and DEAE, equilibrium centrifugation in the presence or absence of detergent, determination of the % binding of detergent and consequent calculation of the protein molecular weight.
I expect that your data will overlap ours if the two phages are similar and I will look forward with interest your publication.  If you have the detailed amino-acid composition of QB I would very much like to compare it with ours and put the comparison in the paper we want to write.
With regard to my intended visit to your laboratory.  I would prefer to come this fall for several reasons, not the least of which is the point that at present our spheres of study obviously overlap and it would probably be mutually advantageous to combine at this stage.  Moreover it would fit in well with my personal and research plans.  So I would definitely prefer to come this fall if it can be arranged.
We will all be delighted to have you visit us here late in April and are looking forward to it.
With best wishes,
David Bishop