# Loop Modeling

## Antigen-antibody modeling

Category:
Loop Modeling

I was getting an error while running the snugdock that I solved using the clean_pdb.py command. When I ran flags file using snugdock @flags file, another error came up saying "the antibody doesn't contain start or end of residue of cdr loop H1. Please check pdb is renumbered properly and passed -numbering scheme option matched the PDB.This could also mean missing density in the cdr loop. Loop modeling application can be used to fill missing residues."

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## genkic mover produced an unwanted HN - CA bond

Category:
Loop Modeling

I ran the tutorial placed in demos/tutorials/GeneralizedKIC/exercise1/ and successfully produced 10 output structures. However, the residue ALA32 that was encompassed by the genkic mover has unwanted HN - CA bond and HN_CB bond. All the 10 output structures have this problem, and I've attached three of them. I tried to FastRelax the strucutre after genkic mover, but the unwanted bonds were still kept.

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## Modelling at defined pH - for pmutscan - pH:mode not working

Category:
Scoring
Loop Modeling
Chemically Modified Residues

Hi all,

I am new to Rosetta and using various Rosetta protocols, primarily remodel and pmutscan, to assess the impact of various mutations on protein stability. I would like to model the protein and associated mutations at acidic pH as this may affect salt bridge formation and overall REU score.

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## Rosetta (antibody_designer) performance

Category:
Loop Modeling

Hi All,

I am building a Rosetta(rosetta_bin_linux_2021.16.61629_bundle) and running the simulation that my customer offerd.

One thing I really want to know and ask you guys is that the performance is okay and how to imporve more.

Here are my environments.

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## [LoopModelerMover] ERROR: Can't build a fold tree from a loop with an unspecified cut point.

Category:
Loop Modeling

Hello,

I am trying to use the LoopModelerMover to relax a couple of loops in a protein complex. I would like to let Rosetta select cutpoints automatically so I leave the cutpoints set to 0. An example script is attached as a text file. I have tried specifying the loops as loop subtags and as a loops file, and in both cases I get this error.

ERROR: Can't build a fold tree from a loop with an unspecified cut point.

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## C-termini remodelling of dimeric structure removes second chain

Category:
Loop Modeling

Dear Rosetta Community,

I am trying to remodel a short C-terminal loop into  a docked dimeric structure consisting of 2 identical proteins and while the modeling itself worked, the output contains only the first protein.  The flags I used are the following:
-in:file:s bestp1.pdb
-remodel:blueprint c-term.remodel
-no_optH false
-ex1
-ex2
-remodel:num_trajectory 1
-remodel:quick_and_dirty

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Category:
Loop Modeling

Dear Rosetta Users,

I would like to build a linker that connects the VH to the VL domain of a single-chain Fv.
The length of the linker is ~15 aa (actually I'm going to build two linkers which differs in term of length).

In the literature, I found a case in which the RosettaRemodel application was used to perform a loop closure with a glycine-serine linker between two domains.

However, the sequence of my linker is known and it must not be changed.
I just need to build -and not design- the linker.

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Category:
Loop Modeling

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## Disulfide Bonds in Loop Modeling

Category:
Loop Modeling

Good Morning,

I was implementing the NGK loop modeling to fill the missing loops in the PDB structure, but the disulfide bonds in the PDB were broken and converted to regular cystines after the modeling. These disulfide bonds are not in the remodeled loop region and I specified '-loops:fix_natsc true'. From the output, it says:

core.conformation.Conformation: Found disulfide between residues 76 166

core.conformation.Conformation: current variant for 76 CYS

core.conformation.Conformation: current variant for 166 CYS

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