Using GDAL translate in Pythonwin

I want GDAL translate in Pythonwin to process some GeoPDFs to GeoTiffs. I can't call up GDAL module in Pywin. I used the OSGeo4 installer for original GDAL install and can leverage GDAL properly from the OSGeo4W.bat file.

My Python and Pywin are from an install of Arc 10.2.2. I created a PythonPath User variable and added C:\Python27\ArcGIS10.2;C:\Python27\ArcGIS10.2\Lib;C:\Python27\ArcGIS10.2\DLLs;C:\Python27\ArcGIS10.2\Lib\lib-tk;C:\OSGeo4W;C:\OSGeo4W\lib;C:\OSGeo4W\lib\tk8.5;C:\OSGeo4W\bin

After a reboot I still can't call up the OSgeo/GDAL module.

While I would like to use GDAL commands in Pythonwin, I have also tried the work around

os.system("gdal_translate -of GTiff " + sourcefile + " " + destinationfile)

which is launching cmd prompts but not processing the files.

Can someone help with sorting out the GDAL module in Pywin or to clue me in on why the os.system command is not calling up GDAL translate.