And so papaya type of fruit contains a special cysteine protease known as papain. Now let's move on to aspartyl or aspartate proteases as well as metallic proteases. So once again from the title, from that name you can infer that instead of having Serene or cysteine inside these active sites of these enzymes, we have aspartic acid. In fact, these enzymes contain two so a pair of aspartic acids. And as we'll discuss in a future lecture, one of those residues takes away an H atom and the other residue basically is used to increase the nucleophilic character of that particular substrate molecule. And Renan or Renin is basically an example of an aspartal protease that is involved in increasing or decreasing so regulating the blood pressure inside our body.