Effect of alanine insertion (P'5) on the reactive centre of alpha 1-antitrypsin

A recombinant mutant of alpha 1-antitrypsin with an inserted alanine in position P'5 (362-363) was compared with wild-type recombinant and plasma alpha 1-antitrypsins. Initial studies showed that contrary to other reports the wild recombinant inhibitor had the same, or even greater, association constants with trypsin and elastases as the plasma inhibitor. The recombinant mutant as predicted had decreased inhibitory activity but no significant alteration in denaturation temperature and it retained the typical serpin S-R change.