Prenylcysteine oxidase that cleaves the thioether bond of prenyl-L-cysteines, such as farnesylcysteine and geranylgeranylcysteine (PubMed:10585463, PubMed:11078725, PubMed:12186880). Only active against free prenylcysteines and not prenylcysteine residues within prenylated proteins or peptides (By similarity). Involved in the final step in the degradation of prenylated proteins, by degrading prenylcysteines after the protein has been degraded (PubMed:10585463). {ECO:0000250|UniProtKB:F1N2K1, ECO:0000269|PubMed:10585463, ECO:0000269|PubMed:11078725, ECO:0000269|PubMed:12186880}. This is the function of ENSG00000116005 (PCYOX1, prenylcysteine oxidase 1).