Covalently attaches a chromophore to Cys residue(s) of phycobiliproteins (Potential). In vitro does not act as a chromophore lyase for ApcA1, ApcA2, ApcB, ApcD, ApcF, CpcB or PecB, the lyase activity is therefore unsure. Induced by nitrogen starvation. Belongs to the CpcS/CpeS biliprotein lyase family.