The invention provides compounds and methods for inhibiting proteases. One aspect of the invention features pro-soft inhibitors which react with an activating protease to release an active inhibitor moiety in proximity to a target protease. In certain instances, compounds inhibit proteasomes and/or post-proline cleaving enzymes (PPCE), such as dipeptidyl peptidase IV. The compounds of the invention provide a better therapeutic index, owing in part to reduced toxicity and/or improved specificity for the targeted protease. Another aspect of the invention provides for the use of the disclosed compounds for treating Type II diabetes, insulin resistance, glucose intolerance, hyperglycemia, hypoglycemia, hyperinsulinemia, obesity, hyperlipidemia, or hyperlipoproteinemia.
