Semenogelin I-derived peptide SgI-52 binds membrane Peroxiredoxin 6 and induces oxidative stress in asthenozoospermic sperm

Infertility is a global health concern, with asthenozoospermia (AZS) being a common male factor. Our previous research demonstrated that the semenogelin I-derived peptide SgI-52 (SgI-52) binds more rapidly and extensively to demembranated sperm and AZS sperm, significantly inhibiting sperm motility and impairing mitochondrial function. However, the specific molecular targets of SgI-52 on sperm and the mechanisms by which it modulates oxidative stress and sperm function remain unclear. This study therefore investigates the interactions of SgI-52 with sperm surface proteins and its impact on oxidative stress. Sperm proteins from AZS donors were extracted to identify SgI-52 targets using affinity chromatography and quantitative proteomics. The interaction with PRDX 6 was analyzed using AlphaFold 3 predictions and biolayer interferometry, and their localization on sperm membranes was determined by immunofluorescence and immunoelectron microscopy. Western blot measured SgI-52 in seminal plasma and PRDX 6 on sperm membranes. Functional assays evaluated the effects of SgI-52 on PRDX 6 enzymatic activity, oxidative stress levels, and mitochondrial membrane potential in sperm. SgI-52 bound to PRDX 6 and co-localized on sperm membranes. Both seminal plasma SgI-52 and membrane-associated PRDX 6 were higher in AZS donors than in normal donors. Functional assays showed that SgI-52 inhibited PRDX 6 activity, leading to increased ROS and MDA levels and mitochondrial dysfunction in sperm. In vitro study, we observed differential expression of SgI-52 and PRDX6 in normal and AZS samples and revealed their interaction, explaining the preferential binding of SgI-52 to compromised sperm. These findings suggest that SgI-52–derived peptides could serve as molecular probes for sperm quality evaluation and sperm selection in assisted reproductive technologies.