HSP-1/2, a major protein of equine seminal plasma, exhibits chaperone-like activity

The major bovine seminal plasma protein, PDC-109 exhibits chaperone-like activity (CLA) against a variety of target proteins. The present studies show that the homologous protein from equine seminal plasma, HSP-1/2 also exhibits CLA and inhibits the thermal aggregation of target proteins such as lactate dehydrogenase, and DTT-induced aggregation of insulin in a concentration-dependent manner. Phosphorylcholine binding inhibited the CLA of HSP-1/2, suggesting that aggregation state of the protein is important for this activity. These results demonstrate that HSP-1/2 functions as a molecular chaperone invitro, and suggest that it may protect other proteins of equine seminal plasma from unfolding/misfolding or aggregation. These results suggest that homologous proteins from the seminal plasma of other mammals also exhibit CLA, which will be physiologically relevant.

► HSP-1/2 shows chaperone-like activity (CLA) against several target proteins in vitro.
► CD and modeling studies show that the structure of HSP-1/2 is largely unordered.
► Binding of the specific ligand, phosphorylcholine to HSP-1/2 decreases its CLA.