International Protease Network

Department of Medicinal Chemistry, Center for Frontier Research in Medicinal Science
Kyoto Pharmaceutical University
Yamashina-ku, Kyoto 607-8412, Japan
Email: kiso@mb.kyoto-phu.ac.jp
Tel: +81-75-595-4635
Fax: +81-75-591-9900
Homepage: http://www.kyoto-phu.ac.jp/labo/yakuhin/

Research

Aspartic proteases are involved in the processing of functional peptides and proteins, and are essential for the sustenance of life of all living beings from virus to mammals. Inhibition of aspartic proteases such as HIV protease, plasmepsin, human renin, and beta-secretase became important targets for therapeutic agents of AIDS, malaria, hypertension, and Alzheimer?s disease, respectively. Based on the substrate transition state, we designed and synthesized a novel class of aspartic protease inhibitors containing the hydroxymethylcarbonyl (HMC) isostere. We have developed substrate-based HIV protease inhibitors. The tripeptide KNI-272 was a highly selective and superpotent HIV protease inhibitor. It exhibited potent antiviral activities with low cytotoxicity. The NMR, X-ray crystallography and molecular modeling studies showed that the HMC group in KNI-272 interacted excellently with the aspartic acid carboxyl groups of HIV protease active site, and thus, the HMC isostere is an ideal transition-state mimic.
We expanded the transition-state mimetic concept to development of inhibitors of malarial aspartic proteases, plasmepsins which were key enzymes in the life cycle of the Plasmodium parasites responsible for malaria. We identified and characterized high affinity plasmepsin II inhibitors containing HMC isostere with high selectivity with respect to human enzyme cathepsin D. Furthermore, we designed and synthesized a series of beta-secretase inhibitors based on the amino acid sequence of Swedish mutant APP. An octapeptide KMI-008 containing HMC isostere as a transition-state mimic exhibited the BACE1 enzyme inhibitory activity. Using KMI-008 as a lead, small-sized compounds were designed, synthesized and found to exhibit highly potent beta-secretase inhibitory activities.

Collaborations

Professor Ernest Freire, Johns Hopkins University, U.S.A.
Professor Ben M. Dunn, Florida University, U.S.A.
Dr. Alexander Wlodawer, National Cancer Institute, U.S.A.
Professor Shoichi Ishiura, University of Tokyo, Japan
Professor Kouichi Sano, Osaka Medical College, Japan
Professor Toshimasa Ishida, Osaka University of Pharmaceutical Sciences, Japan
Professor Akio Adachi, Tokushima University, Japan

Publications

D. Shuto, S. Kasai, T. Kimura, P. Liu, K. Hidaka, T. Hamada, S. Shibakawa, Y. Hayashi, C. Hattori, B. Szabo, S.i Ishiura, Y. Kiso: KMI-008, a novel b-secretase inhibitor containing a hydroxymethylcarbonyl isostere as a transition-state mimic: design and synthesis of substrate-based octapeptides. Bioorg. Med. Chem. Lett., 13, 4273-4276 (2003).

Y. Sohma, Y. Hayashi, T. Ito, H. Matsumoto, T. Kimura, Y. Kiso: Development of water-soluble prodrugs of the HIV-1 protease inhibitor KNI-727: Importance of the conversion time for higher gastrointestinal absorption of prodrugs based on spontaneous chemical cleavage. J. Med. Chem., 46, 4124-4135 (2003).

A. Nezami, T. Kimura, K. Hidaka, A. Kiso, J. Liu, Y. Kiso, D. E. Goldberg, E. Freire: High affinity inhibition of a family of Plasmodium falciparum proteases by a designed adaptive inhibitor. Biochemistry, 42, 8459-8464 (2003).

M. C. Song, S. Rajesh, Y. Hayashi, Y. Kiso: Design and synthesis of new inhibitors of HIV-1 protease dimerization with conformationally constrained templates. Bioorg. Med. Chem. Lett., 11, 2465-2468 (2001).

Y. Kiso, H. Matsumoto, S. Mizumoto, T. Kimura, Y. Fujiwara, K. Akaji. Small dipeptide-based HIV protease inhibitors containing the hydroxymethylcarbonyl isostere as an ideal transition-state mimic. Biopolymers, 51 (1) 59-68 (1999).