April 4, 1949.

De. de Me Doudorcf£f,
Dept. Bacteriology, . - - _
University of California, . | .
Berkeley.

Dear Mike:

I'm looking forward to seeing you at Cinncinnati, but there are a
couple of things that might be taken up first.

A. If you ati have in ind spending sous time hers, cun you give me
any notion of when and how long it would be? I want to be able to reserve
soma iab apace for you, and not have to sandwich you between too
students. Sometime this summer or before the Fall semester (Sept. 19) would
be preferred, but we cun probably aazke any arrange-rent that would sult
your convenience.  —... ,

B. I'd like to do some quantitative differential sugar determinations !
using T. monosa. Can you send ve a slant, possibly with some directions
4 needed? Thanks. . .

C. Not much new on galactosidase; I've been very busy with heterosygotes |

_ dn F. coli —- have a aanuseript in press for the April PYAS. Also, Rel2 ds
lysogenic, and I've had to spend some time on that bypath also. If I haven't
already nentioned this to you, one of the most startling rssults is that
Lac)—- although lactose-"nagative™ when grown on lactose, produces coneiderable
galactosidese, and washed cells ferment lantese vigorously, shen prorwn om
butyk galactoside. This seems to diasoaddte the specificity of enzyme adaptation
from the action of the enzyme once formed. Conversely, lactob'onate, whish
is not utilized at all by the wild type ceils, nor shows any aprvraciably
affinity for mlactosidase, ig very potent in eliciting the formation of the-
enzymes ,

D. Galactosidase, or rather lactase in the present application, was, I hoped,
going to be a cleanont story with ao complications like those in anylosaltase.
That, galactose-negative cells accumulated hexose during Lactose utilization
was rather encouraging. But lately, I've notdoed thet a suporessormicnt .
combination, very mach Like J=252, low, LaofGla- fron Lac~Glu- from Lao/fle/? »
wild typo, ferments lactose about 4times as rapidly as galactose, and still

more effectively than glucose. Cells grown on lactose use butyl~galactoside

as quickly as lactose, so that we are probably dealing with a special mechanisa
for galactoside transfer (to phosphate?, or even to polysaccharide 777). I hhven't
checked yet for glucose accumlations that's one of the purposes that I want

T. monoga for, Like 4-327; (in respect to the secomi glucose) dried cells

do not ferment lactose (although they split ghhactoside), while dried cells of
K-12, of course, do ferment lactose as they do hexose. This is based on just one
experinent. a“

.

In all of this, I expect that we're dealin with sonething vary much analagous
to Green's cyclophorase. His unextracted preparations completely oxidise pyruvate,
and can apparently tranafer HS phosphate during the oxiddtion; the extracted
enzymes put together perform moe$ of the Kreba cycle steps, but with neither
a deperdemoe on no’ a use for phosphate. . ,

For Ginncinnati, I don't intend to say anything slong these lines, whieh |
you are more competent to discuss. Rather, I hope to expound the genetde analysis
and the adaptive properties of lactage.

380 you then, best tegards,

Joshua Lederberg