ET prommermeree

lel

 

WASHINGTON UNIVERSITY

     

SCHOOL OF MEDICINE

DEPARTMENT OF INTERNAL MEDICINE
BARNES AND WOHL HOSPITALS
600 SOUTH KINGSHIGHWAY
ST. LOUIS 10, MISSOURI!

12 April 196]

Dr. Joshua Lederberg

Department of Genetics

stanford University Medical School
Palo Alto, California

Dear Josh:

Kern, Helmreich and I have revised the enclosed manuscript

so as to comply with most of the objections raised by you and Mel

Cohn. The major difficulty we encountered was the matter of whether

or not microsoma! antibodies are attached to ribosomes or to other
components of the microsomal fraction; e.g., endoplasmic reticulum.

The previous experience here was that deoxycholate treatment was
ambiguous in that most of the antibody activity was removed from the
ribosomes but some definitely adhered. Since deoxycholate can obviously
do much more than simply separate the two principle microsomal componen*s
we clearly had no confidence in interpretation of these resuls. But

the deep reservations we had were not, I see now, expressed clearly
enough so that one can now see where Mel's difficulty occurred. Since
having the manuscript returned Milt has repeated the experiments with
deoxycholate and obtained similar results to his previous ones: i.e.,
nearly all of the microsomal anvibody activity is removed from the
particles. Moreover when the residual small amoun> of activity is
normalized for ribosomal protein or RNA or the sum of these two, it is
clear that the antibody activity remaining on the ribosomes is +tremendois~
ly reduced in amount relative to the parental microsomal fraction. In
part the magnitude of this depletion effect of deoxycholate seems greater
To us now than jit did before because we now use the correct extinction
coefficient for ribosomal protein which is surprisingly low (El en=7).

All of this provides no answer of course as to where antibodies attached
in the microsomal fraction and the corresponding segmen’ of the manuscript
nas been re-written so as to make clear as possible that we have no
answer now to this question.

I do not know that we can do any more and look forward to hearing
what your reaction is to the manuscript in its present form. With best
wishes,

Sincerely yours,

/
Wert icChee ya. :

Herman N. Eisen
HNE : vb
ence