I agree with Nay, too much protein if your hair doesnt need it can cause buildup and lead to dryness and breakage.
Some ingredients to look for in protein conditioners are:
Hydrolyzed Wheat protein, hydro. keratin protein, hydro. collagen, hydro. soy (or can be listed as just soy), amino acids (building blocks of protein), hydro. animal protein, gelatin and I THINK placenta is a protein also. (someone correct me if I am wrong)
Everyone's hair responds differently to different types of protein though. I can use products that contain Hydro. keratin protein daily with no problems but products that have hydro. wheat protein (which I have also read is supposed to be a moisturising protein) build up on my hair so quickly and give it a dry, dulling look.
HTH