NCCC(=O)N[C@H](Cc1cc(O)c(O)c(SCC(NC(=O)CC[C@H](N)C(=O)O)C(=O)NCC(=O)O)c1)C(=O)O
PSA is a commonly used medicinal chemistry metric for the optimization of a drug's ability to permeate cells. Please predict psa of this molecule.