Beta-defensin are small cationic antimicrobial peptides. Family members such as beta-defensin 50 (Defb50) has poor antimicrobial activity in its oxidised form, but this improves under reduced conditions [1].

1: Partial deletion of chromosome 8 beta-defensin cluster confers sperm dysfunction and infertility in male mice. Zhou YS, Webb S, Lettice L, Tardif S, Kilanowski F, Tyrrell C, Macpherson H, Semple F, Tennant P, Baker T, Hart A, Devenney P, Perry P, Davey T, Barran P, Barratt CL, Dorin JR; PLoS Genet. 2013;9:e1003826. PMID:24204287