At about 0542 eastern time, a Cessna 206H went off the pavement while taxiing for takeoff at Sarasota/Bradenton International Airport. The pilot was not injured. The pilot said he became distracted in the darkness and missed the turn onto the runway. The aircraft ran off the end of the taxiway into the sand and grass airport infield area, where the nose gear and propeller collided with a concrete wiring junction box.