_ - pwd 15, 1949.

Dr. FP. H. Stodola,
No. Reg. Res. ‘Lab.,
U. S. De Aa,
Peoria, Dlinois.

- Dear Frank,

; I thought I was going to Detroit, where T expected to see you, but
changed my mind, and decided to write you Instead.

You may remember that I asked you once for some lactcbicnate to help
try to work out a scheme for lactcse utilization that would be complicated
enough to squeeze in half a dozen enaymes to correspond the an equivalent
number of genes that we had found. to control lactose fermentation. I think
that we have pretty good evidence that galactosidase 1s the only relevant
. @nzyme, and that the complex genetic control with its implications of a

. many to many rather than a one-te-ons relationship of gene-to-enzyme, has to
‘do with the complex adaptive mechanism. Lactobionate has turned out to be -
uniquely interesting in this respect, as it seems to evoke galactosidase al-
though it does not combine with the enzyme. But, and you've probably guessed
at this, I've run out of the material that you sent ma. KP Link had some

very old crude stuff that I've been working with, but I don't trust it.
if you can spare “dt, I wonder if you could manage 10 - 20 gms of the
cruder material that you sent me as NRRL 2512-29-A, or equivalent, and
possibly half a gram or so of the more purified 2378-7-A for kinetic
‘competitive inhibition studiea.

This result, 4f verifisd would definitely asprate the specificity of
adaptation from that of the enzyme produced. Conversely, a mitant was picked
up which will not adapt to lactose, but when grown on butyl galactoside, the
harvested cella contain galactosidase and whll ferment lactose!

The important point with respect to lactobionate is not merely that it
evokes galactosidase although itd is not utilized by the enzyme, but that
et doas not so auch as react with it, as determined by competition for the
nzyme with o-nitrophenyl galactoside which we are using as a chromogenic =~
subs trate. However, I have to check this result with galactosidase from cells
grown on the lactoblonate » Which unfortunately takes a fair amount of material

‘If, ‘perchance, you are going to the 8. A.B. necting in Cinneinnatt ; ay Oy
next month ttt ‘ry to look you Upe _. oo Ae

Sincerely, a

 

Joshua Lederberg. ~. -- .