Original Repository: Alan Mason Chesney Medical Archives. Daniel Nathans Collection
Reproduced with permission of Maxine Singer.
Restriction Enzymes and the "New Genetics," 1970-1980
11 February 1972
Because Ernest is presently away at a meeting I am writing to you. You mentioned in one of your letters that it might be feasible
to let us have some of the purified H. influenzae restriction enzyme if there were a way to ship it. Early in March there
is such an opportunity -- namely to have some one bring it directly. I have asked Randy Holmes in my lab at NIH to call you.
If enzyme is available he will arrange to have someone come to Hopkins to pick it up and then also arrange for its transport
to Israel (probably by Gary Felsenfeld).
The reason for asking is doubts I have concerning our efforts to purify here. The fraction we have obtained clearly gives
us component II from component I SV40, but we have not seen the 7S species on ph8 sucrose gradients (as per Fig 1 in Danna-Nathans).
We are about to try more enzyme -- but since the opportunity arose to have enzyme brought I thought I better take advantage
of the opportunity in case our preparation doesn't work out.
We had no trouble with the cells. The ones grown at 37 degrees prior to shipping grew up well and
[END PAGE ONE]
[BEGIN PAGE TWO]
our checks with medium minus hemin and DPN showed that it was indeed Hemophilus. Our problems probably come from the assay
we are trying to use. We were not set up for the viscosity assay -- other with substrate or viscometers. We tried to use center
and Richardson's assay which measures conversion of double-stranded circles to irreversibly denatured linear molecules
by absorption of the latter to fillers. The assay works but clearly it is not specific for double-stranded breaks as is the
I had an exuberant letter from Robb Moses -- he is set up and working Houston -- delighted to have his own lab and pleased
with the company of Wakil and Caskey.
The year here has been very interesting and busy so far -- both in the lab and outside. Ernest is, as you know, stimulating,
and I have managed to learn a great deal.
Many thanks in advance for the enzyme -- and also for the previous assistance. Should it be impossible to let us have any
enzyme, please do not hesitate to let us know. Neither Ernest nor I would want to have the request be an imposition on you.