CHROMATOGRAPHIC SEPARATION OF ADEN OS [NE DEAMINASE PROTEINS 
translational modification of a single gene 
product. There was no detectable human 
ADA activity in the mouse ADA region 
when starch gel electrophoresis was used, 
and the mouse ADA isozymes did not ap- 
pear electrophoretically altered as a result of 
the retroviral infection. When CEM cells (a 
human T-cell line) are combined with 3T3 
cells and a mixed cell lysate is fractionated 
on an FPLC Mono Q column, the same sep- 
aration of human and mouse ADA isozymes 
is seen following starch gel analysis of the 
column fractions (data not shown). 
This technique of separation was also de- 
veloped in an effort to have a more sensitive 
measure of the expression of human ADA 
following retroviral-mediated gene transfer 
into monkey bone manow cells. For this 
reason, we needed to show that the human 
ADA expressed from the SAX vector in a 
cultured monkey cell line had properties 
similar to ADA from control human cells 
and could be separated from the endogenous 
monkey ADA. The production of human 
ADA was investigated in CV-1 cells, a mon- 
key kidney cell line, after the introduction of 
Flo. I. Graph of ADA activity from mouse 3T3 cells (closed circles) and human mononuclear white 
Wood cells (open circles) following fractionation of whole cell extracts on separate FPLC columns. ADA 
activity was assayed by measuring the conversion of [8-“C]adenosine to [8-“C]inosine and separating the 
reaction products by thin-layer chromatography. 
Recombinant DNA Research, Volume 12 
[2751 
