PR-39 TFA, a natural proline- and arginine-rich antibacterial peptide, is a noncompetitive, reversible and allosteric proteasome inhibitor. PR-39 TFAreversibly binds to the α7 subunit of the proteasome and blocks degradation of NF-κB inhibitor IκBα by the ubiquitin-proteasome pathway. PR-39 TFA stimulates angiogenesis, inhibits inflammatory responses and significant reduces myocardial infarct size in mice.