Body: <p>Sorry for this very beginner homework question:</p>
  <p>Which of the following linear peptides is consistent with Spectrum = {0 71 99 101 103 128 129 199 200 204 227 230 231 298 303 328 330 332 333}? (Select all that apply.)</p>
  <pre><code>CTV
  
  TCE
  
  QCV
  
  AQV
  
  VAQ
  
  TCQ
  </code></pre>
  <p>I tried to use the molecular weight to deduce the answer, but I failed.</p>
  <pre class="lang-py prettyprint-override"><code>In [1]: from rdkit import Chem
     ...: from rdkit.Chem import Descriptors
  
  In [2]: chemical_string = 'A'
  
  In [3]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [4]: print( Descriptors.ExactMolWt(mol) )
  89.047678464
  
  In [5]: chemical_string = 'C'
  
  In [6]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [7]: print( Descriptors.ExactMolWt(mol) )
  121.019749464
  
  In [8]: chemical_string = 'E'
  
  In [9]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [10]: print( Descriptors.ExactMolWt(mol) )
  147.053157768
  
  In [11]: chemical_string = 'T'
  
  In [12]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [13]: print( Descriptors.ExactMolWt(mol) )
  119.058243148
  
  In [14]: chemical_string = 'Q'
  
  In [15]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [16]: print( Descriptors.ExactMolWt(mol) )
  146.06914218
  
  In [17]: chemical_string = 'V'
  
  In [18]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [19]: print( Descriptors.ExactMolWt(mol) )
  117.078978592
  
  In [20]: 
  <span class="math-container">```</span>
  </code></pre>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-14T18:06:20.363Z
Comments.Text: what kind of spectrum ??
Comments.UserDisplayName: pippo1980
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-14T18:44:53.793Z
Comments.Text: are you trying to accomplish what this server does ? https://iomics.ugent.be/ms2pip/
Comments.UserDisplayName: pippo1980
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-25T02:34:57.020Z
Comments.Text: @pippo1980 Someone told me the following: `The first six fragments are the dehydrated mass of each amino acid, so all tripeptides are "consistent". Then it makes no sense again. I think the question might be something like what combination of (cleaved) tripeptides would have dehydrated masses combined to make this set of masses. Then in the dipeptides, the TCE, QCV, VAQ are inconsistent`
Comments.UserDisplayName: kevin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-27T05:30:48.907Z
Comments.Text: what does 'the dehydrated mass of each amino acid' means ? AA Mw - H2O Mw ? What about N-term-AA and C-term AA ?
Comments.UserDisplayName: pippo1980
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-27T22:38:50.120Z
Comments.Text: @pippo1980 what do you mean by `N-term-AA and C-term AA` ?
Comments.UserDisplayName: kevin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-27T22:39:34.517Z
Comments.Text: @pippo1980 See the [mass composition analysis](https://i.imgur.com/vkZs26B.png)
Comments.UserDisplayName: kevin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-09-28T15:16:39.937Z
Comments.Text: Alanine is 71 = 89 - H2O (18). What about N-term, C-term , first and last aa of polipeptide chain ?
Comments.UserDisplayName: pippo1980
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-10-01T01:53:39.573Z
Comments.Text: @pippo1980 I am not from chemistry background.  May I ask what `N-term, C-term , first and last aa` means ?
Comments.UserDisplayName: kevin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-10-01T07:56:00.403Z
Comments.Text: The free amine end of the chain is called the “N-terminus” or “amino terminus” and the free carboxylic acid end is called the “C-terminus” or “carboxyl terminus, from google could be incorrect
Comments.UserDisplayName: pippo1980
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-10-02T03:14:07.383Z
Comments.Text: @pippo1980 okay, but how does that help to solve this question ?
Comments.UserDisplayName: kevin
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-10-02T06:17:08.640Z
Comments.Text: Was wondering about your mass composition analysis weight, like N e C term AA weights are missing, unless your machine has a resolution power that cannot distinguish that weights differences
Comments.UserDisplayName: pippo1980
Tags: <phylogenetics><homework>
Title: Relationship between molecular weight and linear peptide
ThreadText: # Relationship between molecular weight and linear peptide
  
  (Asked by: username_0 on 2022-09-11)
  
  Sorry for this very beginner homework question:
  
  Which of the following linear peptides is consistent with Spectrum = {0 71 99 101 103 128 129 199 200 204 227 230 231 298 303 328 330 332 333}? (Select all that apply.)
  
  ```
  CTV
  
  TCE
  
  QCV
  
  AQV
  
  VAQ
  
  TCQ
  
  ```
  
  I tried to use the molecular weight to deduce the answer, but I failed.
  
  ```py
  In [1]: from rdkit import Chem
     ...: from rdkit.Chem import Descriptors
  
  In [2]: chemical_string = 'A'
  
  In [3]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [4]: print( Descriptors.ExactMolWt(mol) )
  89.047678464
  
  In [5]: chemical_string = 'C'
  
  In [6]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [7]: print( Descriptors.ExactMolWt(mol) )
  121.019749464
  
  In [8]: chemical_string = 'E'
  
  In [9]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [10]: print( Descriptors.ExactMolWt(mol) )
  147.053157768
  
  In [11]: chemical_string = 'T'
  
  In [12]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [13]: print( Descriptors.ExactMolWt(mol) )
  119.058243148
  
  In [14]: chemical_string = 'Q'
  
  In [15]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [16]: print( Descriptors.ExactMolWt(mol) )
  146.06914218
  
  In [17]: chemical_string = 'V'
  
  In [18]: mol: Chem.Mol = Chem.MolFromFASTA(chemical_string)
  
  In [19]: print( Descriptors.ExactMolWt(mol) )
  117.078978592
  
  In [20]: 
  ```
  
  ```
  
  **Tags:** phylogenetics, homework
  
  > **Comments:**
  > **username_1**: what kind of spectrum ??  
  > **username_1**: are you trying to accomplish what this server does ? https://iomics.ugent.be/ms2pip/  
  > **username_0**: @username_1 Someone told me the following: `The first six fragments are the dehydrated mass of each amino acid, so all tripeptides are "consistent". Then it makes no sense again. I think the question might be something like what combination of (cleaved) tripeptides would have dehydrated masses combined to make this set of masses. Then in the dipeptides, the TCE, QCV, VAQ are inconsistent`  
  > **username_1**: what does 'the dehydrated mass of each amino acid' means ? AA Mw - H2O Mw ? What about N-term-AA and C-term AA ?  
  > **username_0**: @username_1 what do you mean by `N-term-AA and C-term AA` ?  
  > **username_0**: @username_1 See the [mass composition analysis](https://i.imgur.com/vkZs26B.png)  
  > **username_1**: Alanine is 71 = 89 - H2O (18). What about N-term, C-term , first and last aa of polipeptide chain ?  
  > **username_0**: @username_1 I am not from chemistry background.  May I ask what `N-term, C-term , first and last aa` means ?  
  > **username_1**: The free amine end of the chain is called the “N-terminus” or “amino terminus” and the free carboxylic acid end is called the “C-terminus” or “carboxyl terminus, from google could be incorrect  
  > **username_0**: @username_1 okay, but how does that help to solve this question ?  
  > **username_1**: Was wondering about your mass composition analysis weight, like N e C term AA weights are missing, unless your machine has a resolution power that cannot distinguish that weights differences  
  
  ---
  
  ## 0 answers
  
  