Fig. 9.

Proposed Model. When exposed to serum, bacteria experience oxidative stress, whose adverse effects can be mitigated by GSH metabolism, allowing bacterial survival. When exogenous glycine is added to serum, it can be metabolized directly or indirectly into serine and l-cysteine, and oxidation of GSH to GSSG increases while reduction of GSSG to GSH decrease. Thus, the accumulated GSSG and ROS might disrupt membrane integrity to facilitate complement binding.