This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
PDB dc EBI. Alpha and beta proteins ab Cysteine proteinases Cysteine proteinases Papainlike Pro cathepsin EBI dc November Pro cathepsin Files uploaded by Nichalp's script
Page 2023 Free-images.com. All images are Public Domain