Many thanks for your letter of the 1st October. Since writing to you I have, of course, seen the recent issue of the Proc.
Nat. Acad. Sci. containing your last article. Many thanks also for all the information you gave, which is very interesting.
I should like sometime to know if you have any scheme for visualizing how your discrete particles, which are apparently inherited
through the cytoplasm, actually function in promoting enzyme synthesis.
As far as our own work goes, you have presumably seen my last paper on penicillinase adaptation, since I sent you a reprint.
We have since followed that up by investigating the absorption of penicillin sulphur on to the cells, using the same pretreatment
technique as for adaptation experiments, by means of S35-labelled penicillin. We have found that there is a pretty close
correlation between the amount of penicillin sulphur specifically fixed on the cells and the effect of penicillin in stimulating
subsequent production of penicillinase in a penicillin-free medium, following pretreatment at 0 degrees plus thorough washing
of cells. In this particular case at least, there seems to be fairly good evidence that some sort of specific interaction
between penicillin and a specific penicillin receptor within the cells is first necessary in order for the cells to adapt
to penicillinase formation. It is interesting that the amounts of penicillinase sulphur firmly fixed on the cells are exceedingly
small - maximal adaptation effect being achieved after the fixation of about 100 S per cell.
Do you yet know whether you will be coming to the Biochemical Congress in Paris next year?