COMPUTATIONAL EXPLORATION OF THE INTERACTIONS BETWEEN BUFFALO SPERM-DERIVED POLYUNSATURATED FATTY ACIDS AND ANTIFREEZE PROTEINS

Abstract

The cryopreservation of buffalo sperm remains difficult because of the sensitivity of polyunsaturated fatty acids (PUFAs) in the sperm membrane to oxidative destruction. PUFAs, including docosahexaenoic acid (DHA), linoleic acid, eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA), are essential for membrane fluidity, structural integrity, and sperm function. The peroxidation of these bacteria under freezing conditions reduces membrane stability, resulting in decreased motility and fertility. Antifreeze proteins (AFPs), which are known for their distinct ice-binding and ice-growth inhibition capabilities, represent a viable method not only for preventing ice crystal formation but also for interacting with and stabilizing lipid components. The molecular interactions between selected AFPs and important buffalo sperm PUFAs were evaluated in this study via molecular docking and PM6 semiempirical energy optimization. Eight AFP structures from the Type II and Type III classes were docked with the four target PUFAs. The findings demonstrated that all fatty acids had favourable binding energies, with DHA demonstrating the strongest and most stable associations across numerous AFPs, notably with Type III variations such as 1KDE and 1HG7. The contact mechanisms included hydrophobic alignment and hydrogen bonding, indicating structural complementarity between AFP surfaces and PUFA chains. These findings indicate that AFPs may have a dual cryoprotective effect, alleviating oxidative stress while also strengthening the integrity of PUFA-rich sperm membranes. The discovered molecular affinity provides a mechanism for incorporating AFPs into enhanced cryopreservation methods. By understanding the nature of PUFA-AFP interactions, this study helps in the design of physiologically informed strategies aimed at increasing postthaw sperm survival and reproductive results in buffalo and possibly other species.