Aggregated and monomeric forms of protein in boar seminal plasma: Characterization and binding properties

Boar seminal plasma was separated into five protein fractions (I-V) (100, 55, 45, 30, 5-15 kDa) by gel filtration chromatography on Sephadex G-75 SF at pH 7.4. RP HPLC of protein fractions I-V and N-terminal sequencing of their individual components revealed that high-molecular-weight aggregates consisted mainly of DQH sperm surface protein and AQN, AWN, PSP II spermadhesins, while fraction IV consisted of heterodimers of PSP spermadhesins only. Spermadhesins as monomers were present in seminal plasma in a very low amount. Biotinylated fractions I-IV containing AWN, AQN, DQH, and PSP proteins were bound to boar epididymal and ejaculated spermatozoa with the same efficiency. Aggregates containing AWN, AQN, DQH, PSP II proteins (fractions I-III) and teir HPCL-separated monomeric forms interacted with phoshorylcholine.