Met-α₂AP as percent of total α₂AP and by genotype. α₂AP was purified from each plasma of persons with RR (n = 15), RW (n = 15), and WW (n = 5) genotypes and amino-terminal sequences determined by Edman degradation. Percent Met-α₂AP was calculated from picomole recoveries of Met and Asn in the first cycle.