Now let's move on to five and six. So the most common type of fibrous protein that is found inside our body for example it's found in bone, it's found in skin and it's generally found in the areas surrounding our cells. So the extracellular environment, this fibrous protein as you might know is collagen. But collagen must be activated from its pro enzyme form from its zymogen form and the Xymogen form is known as pro collagen. In fact this leads us directly into six. We have another enzyme known as collagenase which is actually responsible for activating the pro collagen into collagen.