The cyclic dipeptide CI-4 [cyclo-(l-Arg-d-Pro)] inhibits family 18 chitinases by structural mimicry of a reaction intermediate.
Houston, D.R., Eggleston, I., Synstad, B., Eijsink, V.G., van Aalten, D.M.(2002) Biochem J 368: 23-27
- PubMed: 12323074 
- DOI: https://doi.org/10.1042/BJ20021034
- Primary Citation of Related Structures:  
1O6I - PubMed Abstract: 
Family 18 chitinases are attractive targets for the development of new inhibitors with chemotherapeutic potential against fungi, insects and protozoan/nematodal parasites. Although several inhibitors have been identified, these are based on complex chemistry, which hampers iterative structure-based optimization. Here we report the details of chitinase inhibition by the natural product peptide CI-4 [ cyclo -(L-Arg-D-Pro)], which possesses activity against the human pathogenic fungus Candida albicans, and describe a 1.7 A (0.17 nm) crystal structure of CI-4 in complex with the enzyme. The structure reveals that the cyclic dipeptide inhibits chitinases by structurally mimicking a reaction intermediate, and could, on the basis of its accessible chemistry, be a candidate for further optimization.
Organizational Affiliation: 
Division of Biological Chemistry and Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K.