Dr. J. Bdonod
Institut Pasteur
28 Rue du Rr. Boux
Paris 15, France

Dear Jacques t

  I hope you will pamion my not having answered your several recent letters
but by nm I am sure you must be accustomed to my poor capacities 88 a corres-
pondent,  On q return from Europe this spring I was overwhelmed with a mass
of accumulated unfinished business and a lot of teaching which has continued
through the summer.
were employed to keep experiments going in the lab.

VirtuaLly all the energy which remained beyond these tasks

Let me briefly suwmarize some of our findings to date.

           First, with

Thisagrees very well with our

respect to the/-galacLosidase, I notiged in your manuscript that you sent
to me that you gav  a value of 1.6 x 10  o

are equivalent.  %e use a micro-nesaler method (hnni).
is achieved by starch ionophoresis.
weight and it is in the neighborhood of rK)O,OOO.  AB a matter of facL, the
enzyme can be s,mn down in preparative Spine0 and in point of fact,  we use
this now routinely to concentrate %e emymt3.  We thirs now prepare enzyme
without any amonim sulfate fractionations,  We can reco-Jer virtually all of
the enzyme in the pure state tluntouched bj. human han?lsfl.

value of 1.66 x 10 % . This as8umes that ow methods for nitrogen determines

This level of purity

We have an estimation of the molecular

With respect to the 'tprsinduction" phenomenon I can say little more than

I have already told you.
with you in Paris.
butyl# galactoside,
free galactoside being the causative agent.

We have confirmed the experiment that I performed

Namely that there is no preinduction effect with the

We have ruled out the possibilibf of small amounts of

Our experiments with stimulatory effects of extracts fmm preinducted cells

are progressing to the extent that re now understand much better the conditions
for testing the activity of the extracts and also for the preparation of
active material.  Ne should soon (as soon as my people come back froill vacation)
know something about the nature of the active agent here.

We have looked into the question of constiuitivity and its probable

cause.  lit present our experiments indicate that it has none.  Re cannot find
anything which has reasonable induc : ive activity in extracts fmm the
constitutive mutant.
in the constitu+,ive mutant by preparations from inducible strains.
inhibitioa is overcome by Lactose.  We have gurified the active agent on a
starch column but at the present time I better not say anything about itx
constitution since I think we are pretty close to having good definite
information on this question.

On the o'rher hand we can inhibit enzyme synthesis

This

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I am writing up now our starch column analysis of the various q-glu-

cosidases and thefifructosidases of yeast.  %e story remains more or less
the same except for a few peculiarities which I will not bdher to detail here.

  %re are several things that I would like to have from you people.  We
have been finished for some time with the tsacer story on precursor and have
been waiting for a manuscript from Me1 80 that we could send the two papers
in together,  X xight add, by the way, that the best figure (less than 2.3$)
we have obtained was done with the starch colunn and with further purification
by specific precipitatioLl.
ment with respect to these papers?

Is it your wish .that we still keep to this arrange-

I would also like from Me1 something which he promised to send, namely

a description of his synthetic procedures 90 that we can undertake here to
manuEacture them in large quantities,

FinaUy,I expect to be in Paris with Helen in the early part of Sept-

ember as well as in the latter part of September.
middle East.
from Paris any time during the month of September so I can arrange my trip
accordingly .

We are on our way to the

Please let me knuw whether you and pur people will. be away

With love to all,

Sincerely yours,

S. Spiegelman

SS:rjs