Given their rich green color, one would expect green string beans to have a high ORAC value. For a vegetable, they test somewhat low. For example, even a white baked potato beats them in how much antioxidants they have. The amount of protein in green beans isn't impressive either: 100 grams of them raw will provide you with only 2 grams of protein. But considering that's only 31 calories worth, obviously one could consume 10x that amount and get a respectable 20 grams of protein for only 310 calories. It may sound like a tall feat, but when you cook them their size will become a fraction.
ORAC Source
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010