Dear Chimera Software Team, 

    I hope this email finds you well. I am writing to seek assistance regarding a challenge I am facing while using the Chimera software. Specifically, I am experiencing difficulties in visualizing my protein structure in ribbon mode. 

    When I load my PDB file and choose the ribbon representation, the resulting visualization appears as linear segments rather than the desired helical structure. I am unsure whether this issue is related to my file or if there is a specific step or setting I am overlooking.

   I would greatly appreciate it if you could provide me with guidance on how to achieve the desired helical ribbon model in Chimera or any insights on potential issues with my file. To assist you in troubleshooting, I have attached the PDB file in question, as well as an image showing the current ribbon visualization. 

   Thank you in advance for your time and support. I look forward to your prompt response. 

 Best regards, Shuyue Luo

the result of my file