Rat liver microsomal palmitoyl-CoA synthetase: subunit structure

Area of Science:

• Biochemistry
• Enzymology

Background:

• Long chain fatty acyl-CoA synthetase (EC 6.2.1.3) is crucial for fatty acid metabolism.
• Previous studies reported a catalytic unit molecular weight of 168,000 daltons.

Purpose of the Study:

• To determine the subunit composition of rat liver microsomal long chain fatty acyl-CoA synthetase.
• To investigate the structural integrity of the enzyme's catalytic unit.

Main Methods:

• Enzyme dissociation using 75% 2-chloroethanol in water.
• Determination of amino and carboxy terminal groups.
• Sedimentation equilibrium analysis.
• Quantitative carboxy terminal analysis.

Main Results:

• Long chain fatty acyl-CoA synthetase completely dissociates into a single polypeptide chain.
• The enzyme possesses one amino and one carboxy terminal group.
• Subunit molecular weight determined as 28,000 +/- 1000 daltons, consistent with previous findings.
• The 168,000 dalton catalytic unit is composed of identical subunits.

Conclusions:

• Rat liver microsomal long chain fatty acyl-CoA synthetase is a multimeric protein.
• The enzyme is composed of identical subunits, each with a molecular weight of approximately 28,000 daltons.