If you work with biomolecular structures and need to convert PDB files to STR or OBJ files for 3D modeling or visualization, there are several tools and methods you can use. Here are the steps to convert a PDB file to STR or OBJ files:

1. Using PyMOL: PyMOL is a popular molecular visualization software that can be used to convert PDB files to STR or OBJ files. Simply open the PDB file in PyMOL, go to File > Save Molecule As, and choose the file format you want to save it as (e.g., STR or OBJ).

2. Writing a Custom Script: If you prefer to write your own script to convert PDB files to STR or OBJ files, you can use a programming language such as Python to read the PDB file and write it out in the desired format. There are libraries available for parsing PDB files, such as Biopython, that can help simplify this process.

3. Using Online Conversion Tools: There are also online conversion tools available that can convert PDB files to STR or OBJ files. Simply upload the PDB file to the tool, select the desired output format, and download the converted file.

4. Converting with UCSF Chimera: UCSF Chimera is another popular molecular modeling and visualization software that can be used to convert PDB files to STR or OBJ files. Open the PDB file in Chimera, go to File > Save As, and choose the file format you want to save it as.

Regardless of the method you choose, it's important to ensure that the desired file format (STR or OBJ) supports the data and features you need for your 3D modeling or visualization. Once you have converted the PDB file to the desired format, you can use it in 3D modeling software or visualization tools to create stunning representations of biomolecular structures.

In conclusion, converting PDB files to STR or OBJ files for 3D modeling or visualization can be done using tools like PyMOL, UCSF Chimera, custom scripts, or online conversion tools. Whichever method you choose, make sure to consider the compatibility and features of the output format for your specific needs.