<p>If I want to find the longest residue count model in PDB that includes Titin, I need to use the statistic &quot;Total Number of Polymer Residues per Deposited Model&quot;:</p>
<p><a href="https://i.sstatic.net/UhfV4DED.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UhfV4DED.png" alt="Search query for &quot;8G4L&quot; with &gt;=167,754 polymer residues" /></a></p>
<p>For looking for helices, the statistic seems to be &quot;Count Per Polymer Chain - Protein helices&quot;, and for beta sheets &quot;Count Per Polymer Chain - Beta-sheets&quot;. These statistics can be combined using the AND operator.</p>
<p>Not quite sure what you mean by &quot;loop&quot; or &quot;Coil&quot;. Disordered protein regions have no associated annotation. You can type words into the &quot;Structure Attributes&quot; search box to find statistics that can be searched and filtered.</p>

CC BY-SA 4.0
2024-06-19T23:41:13.827Z
*Not quite sure what you mean by "loop".* --- Coils (C).
user366312
CC BY-SA 4.0
2024-06-20T00:05:47.847Z
This post doesn't answer my question. My aim is not to search for Titin. My aim is to find some of the proreins with the longest chains.
user366312
CC BY-SA 4.0
2024-06-20T00:22:56.200Z
@user366312 As you were, I was using Titin as a demonstrative example for showing what I believe to be the appropriate residue statistic. If you don't think this answer is useful in solving your problem, then click on the "This Answer Is Not Useful" down arrow.
gringer
CC BY-SA 4.0
2024-06-19T23:05:28.550Z
2024-06-20T00:26:55.833Z
2024-06-20T00:26:55.833Z
gringer
<p>I want to find some globular proteins with some of the longest individual chains that have all three types of secondary structures,, namely helix, sheet, and loop.</p>
<p>So, I tried <a href="https://www.rcsb.org/search?request=%7B%22query%22%3A%7B%22type%22%3A%22group%22%2C%22logical_operator%22%3A%22and%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22group%22%2C%22logical_operator%22%3A%22and%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22group%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22terminal%22%2C%22service%22%3A%22text%22%2C%22parameters%22%3A%7B%22attribute%22%3A%22entity_poly.rcsb_sample_sequence_length%22%2C%22operator%22%3A%22greater_or_equal%22%2C%22negation%22%3Afalse%2C%22value%22%3A20000%7D%7D%5D%2C%22logical_operator%22%3A%22and%22%7D%5D%2C%22label%22%3A%22text%22%7D%5D%7D%2C%22return_type%22%3A%22entry%22%2C%22request_options%22%3A%7B%22paginate%22%3A%7B%22start%22%3A0%2C%22rows%22%3A25%7D%2C%22results_content_type%22%3A%5B%22experimental%22%5D%2C%22sort%22%3A%5B%7B%22sort_by%22%3A%22score%22%2C%22direction%22%3A%22desc%22%7D%5D%2C%22scoring_strategy%22%3A%22combined%22%7D%2C%22request_info%22%3A%7B%22query_id%22%3A%2263a9c0b951c73de84dcad246f45e4000%22%7D%7D" rel="nofollow noreferrer">the following search</a>:</p>
<p><a href="https://i.sstatic.net/BHNYFX9z.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/BHNYFX9z.png" alt="enter image description here" /></a></p>
<p>This search should have at least returned Titin.</p>
<p>However, it returns nothing.</p>
<p>How can I search for globular proteins by residue count in the RCSB database?</p>
<hr />
<p><a href="https://i.sstatic.net/KPb8uh5G.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/KPb8uh5G.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2024-06-19T23:01:05.820Z
What makes you think that there is a >20,000 amino acid structure for TTN in PDB? The longest residue count for structures referenced from [the Wikipedia page](https://en.wikipedia.org/wiki/Titin) is 3,420 monomers (4UOW).
gringer
CC BY-SA 4.0
2024-06-19T23:38:27.403Z
@gringer, see the update.
user366312
CC BY-SA 4.0
2024-06-20T00:17:04.917Z
I'm aware that Titin is "the largest protein chain in your body", but I had trouble finding a PDB model for that complete protein chain. There does seem to be a supercomplex that includes Titin, though: https://www.rcsb.org/structure/8G4L
gringer
<proteins><pdb>
How can I search globular proteins by residue count in the RCSB databse?
# How can I search globular proteins by residue count in the RCSB databse?

(Asked by: username_0 on 2024-06-18)

I want to find some globular proteins with some of the longest individual chains that have all three types of secondary structures,, namely helix, sheet, and loop.

So, I tried [the following search](https://www.rcsb.org/search?request=%7B%22query%22%3A%7B%22type%22%3A%22group%22%2C%22logical_operator%22%3A%22and%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22group%22%2C%22logical_operator%22%3A%22and%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22group%22%2C%22nodes%22%3A%5B%7B%22type%22%3A%22terminal%22%2C%22service%22%3A%22text%22%2C%22parameters%22%3A%7B%22attribute%22%3A%22entity_poly.rcsb_sample_sequence_length%22%2C%22operator%22%3A%22greater_or_equal%22%2C%22negation%22%3Afalse%2C%22value%22%3A20000%7D%7D%5D%2C%22logical_operator%22%3A%22and%22%7D%5D%2C%22label%22%3A%22text%22%7D%5D%7D%2C%22return_type%22%3A%22entry%22%2C%22request_options%22%3A%7B%22paginate%22%3A%7B%22start%22%3A0%2C%22rows%22%3A25%7D%2C%22results_content_type%22%3A%5B%22experimental%22%5D%2C%22sort%22%3A%5B%7B%22sort_by%22%3A%22score%22%2C%22direction%22%3A%22desc%22%7D%5D%2C%22scoring_strategy%22%3A%22combined%22%7D%2C%22request_info%22%3A%7B%22query_id%22%3A%2263a9c0b951c73de84dcad246f45e4000%22%7D%7D):

[![enter image description here](https://i.sstatic.net/BHNYFX9z.png)](https://i.sstatic.net/BHNYFX9z.png)

This search should have at least returned Titin.

However, it returns nothing.

How can I search for globular proteins by residue count in the RCSB database?

---

[![enter image description here](https://i.sstatic.net/KPb8uh5G.png)](https://i.sstatic.net/KPb8uh5G.png)

**Tags:** proteins, pdb
> **Comments:**
> **username_1**: What makes you think that there is a >20,000 amino acid structure for TTN in PDB? The longest residue count for structures referenced from [the Wikipedia page](https://en.wikipedia.org/wiki/Titin) is 3,420 monomers (4UOW).  
> **username_0**: @gringer, see the update.  
> **username_1**: I'm aware that Titin is "the largest protein chain in your body", but I had trouble finding a PDB model for that complete protein chain. There does seem to be a supercomplex that includes Titin, though: https://www.rcsb.org/structure/8G4L  

---

## 1 answers

### Answer by username_1 on 2024-06-19. Score: 1

If I want to find the longest residue count model in PDB that includes Titin, I need to use the statistic "Total Number of Polymer Residues per Deposited Model":

[![Search query for ](https://i.sstatic.net/UhfV4DED.png)=167,754 polymer residues" />](https://i.sstatic.net/UhfV4DED.png)

For looking for helices, the statistic seems to be "Count Per Polymer Chain - Protein helices", and for beta sheets "Count Per Polymer Chain - Beta-sheets". These statistics can be combined using the AND operator.

Not quite sure what you mean by "loop" or "Coil". Disordered protein regions have no associated annotation. You can type words into the "Structure Attributes" search box to find statistics that can be searched and filtered.

> **Comments:**
> **username_0**: *Not quite sure what you mean by "loop".* --- Coils (C).  
> **username_0**: This post doesn't answer my question. My aim is not to search for Titin. My aim is to find some of the proreins with the longest chains.  
> **username_1**: @user366312 As you were, I was using Titin as a demonstrative example for showing what I believe to be the appropriate residue statistic. If you don't think this answer is useful in solving your problem, then click on the "This Answer Is Not Useful" down arrow.  

---

