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International Journal of Peptides
Volume 2012 (2012), Article ID 316432, 7 pages
Research Article

Peptide-Modulated Activity Enhancement of Acidic Protease Cathepsin E at Neutral pH

1Department of Functional Materials Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama-shi, Saitama 338-8570, Japan
2Rational Evolutionary Design of Advanced Biomolecules, Saitama (REDS), Saitama Small Enterprise Promotion Corporation, No. 552, Saitama Industrial Technology Center, 3-12-18 Kami-Aoki, Kawaguchi, Saitama 333-0844, Japan

Received 29 August 2012; Revised 20 October 2012; Accepted 27 October 2012

Academic Editor: Weihong Pan

Copyright © 2012 Masayuki Komatsu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Enzymes are regulated by their activation and inhibition. Enzyme activators can often be effective tools for scientific and medical purposes, although they are more difficult to obtain than inhibitors. Here, using the paired peptide method, we report on protease-cathepsin-E-activating peptides that are obtained at neutral pH. These selected peptides also underwent molecular evolution, after which their cathepsin E activation capability improved. Thus, the activators we obtained could enhance cathepsin-E-induced cancer cell apoptosis, which indicated their potential as cancer drug precursors.