PyMOL选取配体周边残基定点突变时遇报错的技术问询

问题背景 #

我在PyMOL中创建配体ECI 5埃范围内的残基选择集，计划对每个选中残基执行丙氨酸定点突变。脚本能正常生成目标选择集，但执行突变步骤时触发错误：“‘Atom’ has no attribute ‘get_id’”

报错详情 #

“Atom” has no attribute “get_id”
File "C:\Users\will\AppData\Local\Schrodinger\PyMOL2\lib\site-packages\pmg_qt\pymol_qt_gui.py", line 1192, in file_run
self.cmd.run(fname)
File "C:\Users\will\AppData\Local\Schrodinger\PyMOL2\lib\site-packages\pymol\parsing.py", line 470, in run
run_(path, ns_pymol, ns_pymol)
File "C:\Users\will\AppData\Local\Schrodinger\PyMOL2\lib\site-packages\pymol\parsing.py", line 519, in run_file
execfile(file,global_ns,local_ns)
File "C:\Users\will\AppData\Local\Schrodinger\PyMOL2\lib\site-packages\pymol\parsing.py", line 514, in execfile
exec(co, global_ns, local_ns)
File "C:/Users/will/PycharmProjects/Binding Residues/bindingresidue.py", line 10, in
res_id = residue.get_id()[1]

原脚本代码 #

from pymol import cmd


cmd.load(r"C:\Users\will\.pymol\Acb1test.pdb", "Acb1")
cmd.remove("not chain A and not residue ECI")
cmd.select("eci_residue", "chain A and resn ECI")
cmd.select("binding_residues", "(byres (eci_residue around 5))")
protein = "Acb1"


for residue in cmd.get_model("binding_residues").atom:
   res_id = residue.get_id()[1]
   res_name = residue.get_parent().get_resname()


   if res_name == "ALA":
       cmd.wizard("mutagenesis")
       cmd.wizard().set_mode("ser")
       cmd.get_wizard().do_select(f"chain A and residue{res_id}")
       cmd.get_wizard().apply()
   else:
       cmd.wizard("mutagenesis")
       cmd.get_wizard().set_mode("ala")
       cmd.get_wizard().do_select(f"chain A and residue{res_id}")
       cmd.get_wizard().apply()


   cmd.save(r"C:\Users\will\Acb1test\{protein}_{res_id}.pdb")
   cmd.reinitialize()
   cmd.load(r"C:\Users\will\.pymol\Acb1test.pdb", "Acb1")
   cmd.remove("not chain A and not residue ECI")
   cmd.select("binding_residues", "br. (byres (residue ECI around 5))")


cmd.delete("binding_residues")

报错原因 #

1. 遍历对象错误：cmd.get_model("binding_residues").atom返回的是原子对象列表，而非残基对象。你将原子当作残基调用get_id()方法，但PyMOL的Atom类没有该方法，直接触发报错。
2. 重复初始化效率低下：每次突变后执行cmd.reinitialize()再重新加载蛋白，不仅耗时，还容易丢失中间状态。
3. 选择语法错误：residue{res_id}缺少空格，PyMOL无法正确识别残基选择规则，应该写成residue {res_id}。
4. 字符串格式化错误：保存路径中的{protein}_{res_id}未使用f-string语法（缺少f前缀），会导致文件名直接显示{protein}而非实际蛋白名称。

解决方法 #

1. 正确获取残基列表：改用cmd.get_model("binding_residues").residues遍历残基对象，残基对象可直接通过resi属性获取残基ID，通过resn属性获取残基名称，无需调用get_id()。
2. 避免重复初始化：提前保存原始蛋白的副本，每次突变前恢复原始状态，替代重新加载的操作。
3. 修正选择语法：将残基选择语句改为f"chain A and residue {res_id}"，确保空格正确。
4. 修正文件名格式化：将保存路径改为f-string格式，确保变量能正确替换为实际值。

修正后的脚本 #

from pymol import cmd

# 加载原始蛋白并预处理
cmd.load(r"C:\Users\will\.pymol\Acb1test.pdb", "Acb1")
cmd.remove("not chain A and not residue ECI")
cmd.select("eci_residue", "chain A and resn ECI")
cmd.select("binding_residues", "(byres (eci_residue around 5))")
protein = "Acb1"

# 保存原始蛋白副本，避免每次重新加载
cmd.create("Acb1_original", "Acb1")

# 获取绑定残基的残基列表（而非原子列表）
residue_list = cmd.get_model("binding_residues").residues

for res in residue_list:
    res_id = res.resi
    res_name = res.resn

    # 恢复原始蛋白状态
    cmd.delete("Acb1")
    cmd.create("Acb1", "Acb1_original")

    # 执行定点突变
    cmd.wizard("mutagenesis")
    if res_name == "ALA":
        cmd.get_wizard().set_mode("ser")
    else:
        cmd.get_wizard().set_mode("ala")
    cmd.get_wizard().do_select(f"chain A and residue {res_id}")
    cmd.get_wizard().apply()
    cmd.set_wizard()  # 关闭突变向导

    # 保存突变后的结构
    save_path = fr"C:\Users\will\Acb1test\{protein}_{res_id}.pdb"
    cmd.save(save_path, "Acb1")

# 清理临时对象
cmd.delete("Acb1_original")
cmd.delete("binding_residues")

内容的提问来源于stack exchange，提问作者Shayan Joarder