Get access
Advertisement

Docking studies and model development of tea polyphenol proteasome inhibitors: Applications to rational drug design

Authors

  • David M. Smith,

    1. Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, and Departments of Biochemistry and Molecular Biology and Interdisciplinary Oncology, College of Medicine, University of South Florida, Tampa, Florida
    Search for more papers by this author
  • Kenyon G. Daniel,

    1. Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, and Departments of Biochemistry and Molecular Biology and Interdisciplinary Oncology, College of Medicine, University of South Florida, Tampa, Florida
    Search for more papers by this author
  • Zhigang Wang,

    1. Department of Chemistry, McGill University, Montreal, Quebec, Canada
    Search for more papers by this author
  • Wayne C. Guida,

    1. Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, and Departments of Biochemistry and Molecular Biology and Interdisciplinary Oncology, College of Medicine, University of South Florida, Tampa, Florida
    2. Department of Chemistry, Eckerd College, St. Petersburg, Florida
    Search for more papers by this author
  • Tak-Hang Chan,

    1. Department of Chemistry, McGill University, Montreal, Quebec, Canada
    Search for more papers by this author
  • Q. Ping Dou

    Corresponding author
    1. Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, and Departments of Biochemistry and Molecular Biology and Interdisciplinary Oncology, College of Medicine, University of South Florida, Tampa, Florida
    • Barbara Ann Karmanos Cancer Institute, and Department of Pathology, Wayne State University School of Medicine, 508 & 516 HWCRC, 110 E. Warren Ave., Detroit, MI 48201
    Search for more papers by this author

Abstract

Previously, we demonstrated that natural and synthetic ester bond-containing green tea polyphenols were potent and specific non-peptide proteasome inhibitors. However, the molecular mechanism of inhibition is currently unknown. Here, we report that inhibition of the chymotrypsin activity of the 20S proteasome by (−)-epigallocatechin-3-gallate (EGCG) is time-dependent and irreversible, implicating acylation of the β5-subunit's catalytic N-terminal threonine (Thr 1). This knowledge is used, along with in silico docking experiments, to aid in the understanding of binding and inhibition. On the basis of these docking experiments, we propose that (−)-EGCG binds the chymotrypsin site in an orientation and conformation that is suitable for a nucleophilic attack by Thr 1. Consistently, the distance from the electrophilic carbonyl carbon of (−)-EGCG to the hydroxyl group of Thr 1 was measured as 3.18 Å. Furthermore, the A ring of (−)-EGCG acts as a tyrosine mimic, binding to the hydrophobic S1 pocket of the β5-subunit. In the process, the (−)-EGCG scissile bond may become strained, which could lower the activation energy for attack by the hydroxyl group of Thr 1. This model is validated by comparison of predicted and actual activities of several EGCG analogs, either naturally occurring, previously synthesized, or rationally synthesized. Proteins 2003. © 2003 Wiley-Liss, Inc.

Get access to the full text of this article

Ancillary