Physical and chemical characterization of a horse serum carboxylesterase.

The research characterizes a type of enzyme found in horse serum known as serine carboxylesterase by detailing its amino acid composition, peptide mapping, and molecular aspects. The study develops a protocol using reversed-phase high-performance liquid chromatography for homogenous preparations of this enzyme and identifies key differences from similar carboxylesterases found in other mammals.

Objective of the Research

• The main goal of this research was to thoroughly characterize the serine carboxylesterase enzyme found in horse serum. This involved analyzing its amino acid composition, peptide mapping, molecular and subunit weights, and particularly focusing on the sequencing of amino acids around the essential active site, the serine residue.

Methods and Approach

• To achieve the above objective, the researchers developed a protocol. The protocol involved using reversed-phase high-performance liquid chromatography as the final step to obtain homogeneous preparations of horse serum carboxylesterase.
• The study started with a partially purified mixture that contained approximately 55% carboxylesterase to produce sufficient amounts for determining the amino acid composition and for creating peptide maps.

Results and Findings

• The researchers found that the amino acid composition, as well as the subunit weight of the horse serum carboxylesterase, was similar to corresponding values reported for other serine carboxylesterases.
• One key difference, however, was the amino acid sequence of the tryptic digest fragment that contains the essential nucleophilic seryl residue. This sequence was found to significantly differ from the corresponding sequences of other mammalian serine carboxylesterases, underscoring unique characteristics specific to the horse serum enzyme.

Significance of the Research

• The study’s findings could be crucial in understanding how different types of the same enzyme vary across species. This, in turn, can potentially impact various scientific fields including biochemistry, pharmacology, and veterinary sciences.
• The developed protocol can aid in future studies by providing a method to isolate homogeneous preparations of carboxylesterase from horse serum. This can facilitate deeper research into the enzyme’s structure and function across various species.