Amino acid sequence of phospholipase A2 from horse pancreas.

This study presents the complete amino acid sequence of phosphlipase A2, an enzyme from horse pancreas. This enzyme is made up of a single chain of 125 amino acids, and is related in structure to similar enzymes in snake venom and pig pancreas.

Objective and Methodology

• The research aimed at determining the complete amino acid sequence of phosphlipase A2 from the horse pancreas. The protein is composed of a single polypeptide chain of 125 amino acids with a molecular weight of 13,927. The protein chain is held together by seven disulfide bridges.
• The sequence determination was done by automated Edman degradation, a process of sequencing amino acids in a protein, of the intact protein and several of the large peptide fragments.
• To analyze the smaller peptides, manual Edman degradation was performed.
• To get fragmentation of the peptide chain, enzymatic digestion was performed using trypsin, chymotrypsin, and thermolysin. These are enzymes used to break down protein.
• To find the final overlap, the researchers digested the polypeptide with a staphylococcal protease specific for glutamoyl bonds, i.e., an enzyme that cuts proteins at glutamoyl bonds.

Findings and Conclusion

• By undertaking these procedures, the researchers were able to show homology between phospholipase A2 from horse pancreas and snake venom phospholipases A2.
• The horse pancreas enzyme is also closely related to the enzyme from porcine (pig) pancreas, with the caveat that some revision should be applied to the previously published amino acid sequence of the porcine phospholipase A2 for accurate comparison.
• The discovery of this homology may have implications for the study of these enzymes and their functions, as well as their potential uses in medicine or biotechnology.