Cysteine (Cys, C)
neutral, nonpolar amino acid
after deprotonation (pKS = 8,5), it contains a negatively charged thiolate center
is found in the terminal and bridging coordination of metal ions
favored metal ions:Cu+, Zn2+, Cu2+, Fe3+, Fe2+, Ni+, Ni2+, Ni3+,
Mo4+, Mo5+, Mo6+
