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
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?