Characterization of α₂-macroglobulin from plasma of cystic fibrosis patients and controls

The physical, kinetic, and isoelectric focusing properties of native α₂-macroglobulin from cystic fibrosis and control plasmas were studied. No differences were found in the esterolytic activity levels of control, obligate heterozygote, and cystic fibrosis plasmas. Stability studies indicated that both control and cystic fibrosis α₂-macroglobulin retained full activity for at least 8 months at -20°C, a week at 0-4°C, 11 hr at 50°C, and showed no differences in thermostability at several preincubation temperatures. The microheterogeneity of native α₂-macroglobulin was studied by column isoelectric focusing of five control and five cystic fibrosis plasmas. The number and pI values of the isoelectric forms between pH 4.5-8.0 were quite similar for both groups even though consistently less cystic fibrosis α₂-macroglobulin activity was recovered after isoelectric focusing.