1470 Journal of Medicinal Chemistry, 1986, Vol. 29, No. 8 in treating emphysema in humans. This is not surprising since the alkylating moieties in these inhibitors might render them toxic when used on a continuous basis. 12 To be suitable for human use, an enzyme inhibitor has to show a high degree of selectivity and must have minimal toxic side effects. As a result, many drugs are molecules that reversibly bind to specific enzymes or receptor ...