Novel Variants of Angiotensin Converting Enzyme-2 of Shorter Molecular Size to Target the Kidney Renin Angiotensin System

Wysocki, Jan; Schulze, Arndt; Batlle, Daniel

To compare the enzymatic activities of highly purified, enzymatically active short ACE2 proteins, we tested their ability to cleave its main natural substrate, Ang II (1-8), to form Ang (1-7). This was measured by an assay measuring the release of the C-terminal amino acid, phenylalanine, which is formed as a byproduct in the cleavage of Ang II (1) (2) (3) (4) (5) (6) (7) (8) to Ang (1-7) [25] . The relative enzymatic potency of the short rACE2 fragments was determined by comparison with equivalent molar amounts of the intact rACE2 (740 AA long), which was used as a benchmark. For assessment of activity levels, the Michaelis-Menten model was used to derive the parameters of catalytic kinetics such as Km and Kcat [15] .