Catalyzes the production of 4-hydroxyphenylacetaldehyde (HPAA) directly from L-tyrosine, tyramine not being formed as an intermediate (PubMed:22266321, PubMed:23204519, PubMed:31682615). Catalyzes both the decarboxylation and deamination of L-dopa to 3,4-dihydroxylphenylacetaldehyde (DHPAA) (PubMed:31682615, PubMed:22266321). H(+) + H2O + L-tyrosine + O2 = (4-hydroxyphenyl)acetaldehyde + CO2 + H2O2 + NH4(+) H(+) + H2O + L-dopa + O2 = 3,4-dihydroxyphenylacetaldehyde + CO2 + H2O2 + NH4(+) Homodimer. Induced by fungal elicitor (PubMed:8420986). Induced by methyl jasmonate (PubMed:22266321). TYDC-2 from parsley can be used in E.coli to produce 3,4-dihydroxyphenylacetaldehyde, a direct precursor of hydroxytyrosol, which is a natural compound from olive oil with a strong antioxidant activity. Belongs to the group II decarboxylase family.