Screening of Small Peptide Against Ischemic Fatty-Acid Binding Protein (FABP)

A low-molecular-weight cytoplasmic protein called heart-type fatty acid-binding protein (H-FABP) is released by cardiac myocytes during an ischemic episode. The normal serum level of FABP is around 3.5 ± 0.4 ng/ml (males), 3.9 ± 0.4 ng/ml (females), while the cutoff value of H-FABP in case of acute myocardial infarction (AMI) is 21.85 ng/ml within 3 hours. In case of angina pectoris, ischemic patients can be distinguished from non-ischemic patients and treated appropriately by detecting the presence of serum H-FABP in a point-of-care (POC) diagnostic approach. As the mortality rate due to coronary heart disease is on the rise worldwide, serum H-FABP levels can act as a diagnostic marker to assist in the prediction of probable cardiac arrest. In the present work, a small peptide against H-FABP has been screened by phage DNA library screening, which can be used for the development of a rapid and accurate diagnostic system for serum H-FABP. The cloning, expression and purification of the H-FABP protein in bacteria and screening of a 12 amino-acid long screened peptide with moderate affinity for binding to H-FABP is reported. The interaction of the said peptide with H-FABP was confirmed by in-silico methods like molecular docking and molecular dynamics simulation. The affinity of the peptide binding to H-FABP was assessed using Isothermal Titration Calorimetry (ITC). A spontaneous process is indicated by ΔG (-7.98 kcal mol^-1) values, but an endothermic interaction activity is implied by positive ΔH (3.11 kcal mol^-1) values. In a futuristic approach, this peptide can be exploited for the development of an accurate and early detection technique for heart ischemia.