Биоконформационни взаимодействия между липопротеини от яйчен жълтък и протеини от семинална плазма и ролята им върху биологичните параметри на сперматозоиди от нерез при нискотемпературно съхранение на 40C

The storage of sperm cells at low temperatures causes alterations, affecting not only the acrosome, but also the intracellular structures (Bailey J et al, 2000). Boar spermatozoa demonstrate high sensitivity to low temperatures. One reason is the decrease in the phospholipids content and in particular the loss of phosphatidylcholine (PC) and phosphatidyl ethanolamine (PEA) found during cryopreservation of boar and ram spermatozoa (Derin-Bennett et al, 1973). This is why different protectors, including egg yolk, are being supplemented into the sperm diluents and storage media. It is considered that the egg yolk covers the sperm plasma membrane from the outside, which defines it as an extracellular protector, and as a result a hydrophobic phase is created, preventing the movement of water and electrolytes between the cell and its environment. Our research established that one of the main reasons for the poor performance during low temperature storage of boar sperm is associated with the plasma membrane and in particular with the sperm acrosome. In the present study a different protective approach for boar sperm is attempted by means of the effect of water - soluble lipoproteins, isolated by gradient separation. After retreating the egg yolk by gradient separation, 2 fractions were obtained and were analyzed and characterized by 10% dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The results demonstrate that fraction 1 contains lipoproteins with molecular weight (MW) from 24 to119 kDa, while in fraction 2 predominate the proteins with MW from 45 to 100 kDa. By High performance liquid chromatography analysis (HPLC), an attempt was made to characterize the interaction between the egg yolk lipoproteins and the boar seminal plasma proteins. By chromatograms we obtained evidence for intermolecular interactions between egg yolk lipoproteins and SPP. A new bio-conformational structure was formed, presented as a well-defined peak at 12.362 min. In this peak are contained proteins with MW between 12.400 and 29 kDa.