Isolation and characterization of rabbit plasma alpha-1-antiproteinase E

Area of Science:

• Biochemistry
• Protease Inhibitor Research

Background:

• Alpha-1-antiproteinase (alpha-1-antitrypsin) is a key protease inhibitor.
• Rabbit plasma contains multiple isoforms of alpha-1-antiproteinase.

Purpose of the Study:

• To purify and characterize alpha-1-antiproteinase E from rabbit plasma.
• To investigate the inhibitory activities and properties of alpha-1-antiproteinase E.

Main Methods:

• Sequential chromatography on hydroxyapatite and anion-exchange columns for purification.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to assess complex formation.
• Enzyme inhibition assays and chemical modification (N-chlorosuccinimide) to determine activity and stability.

Main Results:

• Alpha-1-antiproteinase E was successfully purified.
• The E form formed complexes with trypsin, chymotrypsin, elastase, plasmin, and pancreatic kallikrein.
• Alpha-1-antiproteinase E stoichiometrically inhibited elastase, moderately inhibited chymotrypsin, and gradually inhibited trypsin.
• The F form showed differential inhibition patterns, favoring trypsin.
• Oxidative inactivation varied between the E and F forms.

Conclusions:

• Alpha-1-antiproteinase E exhibits distinct inhibitory profiles against various serine proteases.
• The reactive center of alpha-1-antiproteinase E influences its interaction with different proteases.
• Isoform-specific properties of alpha-1-antiproteinase are crucial for its diverse physiological roles.