Effect on protein phosphatase activity of peptide backbone modification and truncation of the autoinhibitory domain peptide of calcineurin.

Solid-phase synthesis of the autoinhibitory domain of calcineurin, CaN A467–491, also produced [aspartimide477]CaN A467–491 and [iso-Asp477]CaNA467–491 when Boc-based chemistry was employed. In addition, the truncated peptide CaN A467-488 was obtained when Fmoc-based chemistry was employed. All four peptides proved to be effective inhibitors of protein phosphatase activity of calcineurin. The full-length peptide and the C-terminally truncated peptide (CaN467-488) were indistinguishable, with Ki values of 28 ± 3 and 31 ± 5 μM respectively. The internally modified peptides, [iso-Asp477]CaN A467–491 and [aspartimide477]-CaN A467–491, possessed lower inhibitory potencies (Ki values of 87 ± 10 and 55 ±3 μM, respectively).©Munksgaard 1996.