Corza6 TFA is a potent and selective human voltage-gated proton channel (hHv1) peptide inhibitor. Corza6 TFA binds to the external voltage sensor domain (VSD) loop in hHv1 with a Kd of ~1 nM at the natural, hyperpolarized resting membrane potential (RMP) of mammalian cells. Corza6 TFA allows capacitation in sperm and permits sustained reactive oxygen species (ROS) production in white blood cells (WBCs) [1].