C_beta = Atom('CH2')
S_gamma = Atom('SH')
bonds = [Bond(S_gamma, C_beta), ]
pdbmap = [('CYS', {'CB': C_beta, 'SG': S_gamma, }, ), ]
amber_atom_type = {C_beta: 'CT', S_gamma: 'SH', }
name = 'cys_sidechain'
