The Grenadian quarter miler raced ahead on the final bend to edge 2008 Olympic champion, the USA's Lashawn Merritt, into second place Saturday, reports Xinhua.
Luguelin Santos of the Dominican Republic, the silver medallist from last summer Games, was third, more than a second behind James, who crossed the line at a season's best and world leading 44.02 seconds.
Trinidad and Tobago's Lalonde Gordon, the bronze medallist from London finished in fifth place.
In another re-run between gold and silver medallists from London 2012, Jamaica's Shelly-Ann Fraser-Pryce claimed victory in the 100m ahead of rival Carmelita Jeter, with the American settling for third place.
Nigerian Blessing Okagbare finished second.
Fraser-Pryce claimed a season's best time of 10.93 in Shanghai, the second meet of the Diamond League calendar.
"I feel very relaxed. I came here to win and just see how I would do," she said after her win.
The double Olympic champion also said she would race in both the 100m and 200m at the World Championships in Moscow in August.
--IANS (Posted on 19-05-2013)