What do you mean by oxidising?
All I can say from what I know is that leucine, taken by itself on an empty stomach will be far better assimilated and play its role better than the leucine contained in whey protein. From my viewpoint, when protein containing a complete aminos acide profile is digested, diverse aminos work against each other for assimilation, thus the amount of leucine contained in a scoop of whey protein is inferior to the same amount taken by itself, on an empty stomach or before a meal. The same goes for glutamine...
Feel free to correct me if i'm wrong.