Using GDAL translate in Pywin

I want GDAL translate in Pywin 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 Rebooted and still can't call up the OSgeo module.

While I would like to use GDAL commands in Pywin, 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.

So I would like someone to point 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.