Structural Diversity and Analytical Characterization of Acylhomocarnitines

Area of Science:

• Biochemistry
• Metabolomics
• Analytical Chemistry

Background:

• Homocarnitine is a carnitine analog derived from microbiome metabolites.
• Fatty acyl-homocarnitines represent a previously uncharacterized class of mammalian metabolites.
• Understanding these metabolites is crucial for carnitine metabolism research.

Purpose of the Study:

• To develop and validate methods for measuring fatty acyl-homocarnitines.
• To characterize the enzymatic synthesis and cellular production of these compounds.
• To differentiate acyl-homocarnitines from isomeric acyl-carnitines.

Main Methods:

• Liquid chromatography-mass spectrometry (LC-MS) was employed for metabolite measurement.
• Enzyme assays using carnitine acetyltransferase were performed.
• Isotope tracer studies with ¹³C₃-homocarnitine were conducted in vitro.
• Ion dissociation analyses were used to identify diagnostic product ions.

Main Results:

• Fatty acyl-homocarnitines were identified as homologs of acyl-carnitines, with an additional carbon in the fatty acid chain.
• Carnitine acetyltransferase converts short-chain fatty acyl-CoAs to acyl-homocarnitines.
• Mammalian cells were shown to produce short-, medium-, and long-chain acyl-homocarnitines.
• Specific analytical markers were established to distinguish acyl-homocarnitines from acyl-carnitines.

Conclusions:

• The study characterizes a new family of mammalian metabolites, fatty acyl-homocarnitines.
• Novel analytical strategies enable the differentiation of acyl-homocarnitines from acyl-carnitines.
• These findings advance the understanding of carnitine analogs and their metabolic roles.