Pulmonary angiotensin-converting enzyme antienzyme antibody

Area of Science:

• Biochemistry
• Immunology
• Enzymology

Background:

• Angiotensin-converting enzyme (ACE) plays a crucial role in the renin-angiotensin system.
• Antibodies can be generated to study enzyme function and distribution.
• Quantifying anticatalytic activity is essential for understanding enzyme inhibition.

Purpose of the Study:

• To develop a method for quantifying anticatalytic activity in goat antibodies against rabbit ACE.
• To purify and characterize these anticatalytic antibodies.
• To investigate the immunological properties and distribution of ACE in various rabbit tissues and fluids.

Main Methods:

• Diethylaminoethylcellulose chromatography and Sepharose column chromatography for antibody purification.
• Enzyme inhibition assays using substrates like hippurylhistidylleucine, angiotensin I, and bradykinin.
• Development of a competitive radioimmunoassay using radioiodinated ACE.

Main Results:

• Antibodies purified 90-fold showed anticatalytic activity against ACE.
• Different antibody fractions inhibited hydrolysis of various substrates, suggesting broad anticatalytic effects.
• Evidence indicated a single antibody molecule can bind two enzyme molecules, with 18% targeting catalytic determinants.
• ACE was immunologically identified in rabbit kidney, brain, and serum, similar to lung ACE.
• Seminal plasma ACE showed similar anticatalytic activity but lower immunoreactivity compared to lung ACE.

Conclusions:

• A robust method for quantifying anticatalytic antibodies against ACE was established.
• The antibodies effectively inhibit ACE activity and recognize determinants influencing catalysis.
• ACE is immunologically conserved across multiple rabbit organs and fluids, with some variations in immunoreactivity.