sidechain = Group('cyx_sidechain')
peptide = Group('peptide_ct')
bonds = [Bond(peptide.C_alpha, sidechain.C_beta), ]
symbol = 'Cy:': H_delta_2, '2HE': H_epsilon_2, '1HD': H_delta_1, '1HE': H_epsilon_1, 'CE2': C_epsilon_2, 'CE1': C_epsilon_1, 'CD1': C_delta_1, 'HH': H_eta, 'CZ': C_zeta, 'CG': C_gamma, 'CB': C_beta, 'OH': O_eta, 'CD2': C_delta_2, }, ), ]
pdb_alternative = {'HD1': '1HD', 'HD2': '2HD', 'HE1': '1HE', 'HE2': '2HE',
                   'HOH': 'HH'}
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