ADSL is ADSL is ADSL. It's interchangeable with the entire world. My modems from the UK work just fine in the US or Australia or mainland Europe.
Türk Telekom uses Thompson SpeedTouch equipment, which is pretty standard.
Now, if they have service or not, that's a different issue.
The biggest problem is going to be the 110V-220V conversion. Make sure the transformer can handle it. Most do, but it's not a 100% guarantee. Plus they use euro standard plugs, so you will need an adapter to plug in.
