Use of a non-extraction HPLC technique for measuring angiotensin-converting enzyme under optimum conditions

SUMMARY. A non-extraction high performance liquid chromatography assisted method for the measurement of angiotensin-converting enzyme in serum has been developed. Serum containing the enzyme was incubated with the synthetic substrate, furylacryloylphenylalanylglycylglycine at a concentration approaching 10 times the apparent Km, prior to injection onto a shielded hydrophobic reverse phase high performance liquid chromatography column. This allowed the product to be separated and measured directly without the need for a time consuming protein extraction step. The method is enzymatically sound and avoids the methodological problems associated with automated kinetic assays. Additional key phrases: synthetic substrate; direct injection of biological material; shielded hydrophobic reverse phase column; monitoring treatment of sarcoidosis Angiotensin-converting enzyme (ACE, EC 3.4.15.1, dipeptidyl carboxypeptidase) is a mem-brane-bound glycoprotein located mainly on the capillary endothelium ' where it cleaves a dipep