1. The role of conserved residues of chagasin in the inhibition of cysteine peptidases.
- Author
-
dos Reis FC, Smith BO, Santos CC, Costa TF, Scharfstein J, Coombs GH, Mottram JC, and Lima AP
- Subjects
- Amino Acid Sequence, Animals, Base Sequence, Cysteine Proteinase Inhibitors chemistry, DNA Primers, Molecular Sequence Data, Mutagenesis, Site-Directed, Protozoan Proteins chemistry, Protozoan Proteins genetics, Sequence Homology, Amino Acid, Trypanosoma cruzi enzymology, Conserved Sequence, Cysteine Proteinase Inhibitors pharmacology, Protozoan Proteins pharmacology
- Abstract
We have evaluated the roles of key amino acids to the action of the natural inhibitor chagasin of papain-family cysteine peptidases. A W93A substitution decreased inhibitor affinity for human cathepsin L 100-fold, while substitutions of T31 resulted in 10-100-fold increases in the K(i) for cruzipain of Trypanosoma cruzi. A T31A/T32A double mutant had increased affinity for cathepsin L but not for cruzipain, while the T31-T32 deletion drastically affected inhibition of both human and parasite peptidases. These differential effects reflect the occurrence of direct interactions between chagasin and helix 8 of cathepsin L, interactions that do not occur with cruzipain.
- Published
- 2008
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