Mari,
Wheat gluten, usually called vital wheat gluten, is what you have when most of the starch is removed from wheat flour. In normal baking only a small amount is added to recipes. Because of the spongey texture it gives bread you need to mix it with other flours like oat, soy, almond, rye, and wheat bran and flax seed meal also help with the texture. I buy wheat gluten in the bulk section at my health food store, I've also seen Bob's Red Mill brand in the grocery store. It has 24 carbs per cup.
The easy bread recipe has 2g carbs with 18 slices, not sure about calories, and the other bread recipe has approx 2.6g carb per 18 slices. Just found another recipe:
2 cups oat flour
3/4 cup wheat gluten
1/4 cup ground sunflour seeds (or half sesame & sunflower)
1 tsp salt
1 tbsp sugar
2 tbsp rapid rise yeast
1 tsp baking powder
1/2 cup buttermilk (I didn't have any so I used watered down sour cream)
1 cup warm water (more or less..enough to form a ball)

I had my bread machine mix, knead and rise the bread, then I baked it in my oven at 350 in a larger loaf pan(30-45 min)
If you can get 35 slices out of a large loaf it's 4g carb.
I really liked this recipe.