Significance of Hydrogen Bonding at the S1′ Subsite of Calpain I

alpha-Ketohydroxamates were synthesized as bioisosteres of alpha-ketoamides. The alpha-ketohydroxamates were generally more potent than the corresponding alpha-ketoamides. The potency of the compounds suggests that hydrogen bonding and steric bulk of substituents on the nitrogen atom of the ketoamide moiety influence calpain inhibition.