Inverted Protein: Does Sequence Matter?

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In summary, the inverted sequence would produce a different protein because the ends of the protein would be different.
  • #1
Good day! :oldsmile:

Imagine the mRNA with some nucleotide sequence that (after translation) will give us such polypeptide chain:

L-Alanine (first, in the beginning of translation) - L-Arginine - L-Asparagine - L-Aspartic acid - L-Cysteine - L-Glutamic acid - L-Glutamine - Glycine (last, in the end of translation)

Such (or imagine longer one, its length is not crucial in my question) chain will fold after translation and we will get some certain protein.

Now imagine the polypeptide chain with inverted sequence, that is first we get (from ribosome) Glycine, then L-Glutamine and so on:

Glycine - L-Glutamine - L-Glutamic acid - L-Cysteine - L-Aspartic acid - L-Asparagine - L-Arginine - L-Alanine

This chain will also fold, but what we will receive? The same protein?

If the folding process depends only on polypeptide contents (number of amino acids, their chemical properties and sequence) then this “invertness” would not matter and we should get two identical proteins, right?

But if the folding process (and final product) begins as soon as polypeptide chain (more precisely its part) exits ribosome then we will have different amino acid sequencing to fold, in first case we have L-Alanine - L-Arginine - L-Asparagine…………… and in second case: Glycine - L-Glutamine - L-Glutamic acid…………….

So, what do you think? :oldeyes:
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  • #2
Eagle9 said:
If the folding process depends only on polypeptide contents (number of amino acids, their chemical properties and sequence) then this “invertedness” would not matter and we should get two identical proteins, right?
By the sequence, the your protein would still be different because to two ends of the proteins would be different (COOH at one end vs. NH2 at the other). The amino acids with the different terminations would change when the direction of synthesis is changed.
To make them the same, the protein sequence would have to be a palindrome. The both ends would match up with the original.

If only the ends were palindromic and the middle was not, there is the risk that the protein being synthesized would fold up (gong from a string of amino acids to the final 3D structure of the protein) in a different manner (based on the different sequence of amino acids being inserted into the developing protein as it comes out of the ribosome. The folding a protein undergoes can be sequence specific for local regions with different amino acid sequences.
  • #3
A Bill noted, polypeptide sequences have a polarity to then and one end is not equivalent to the other.

In some cases, it is possible to re-arrange a protein sequence through circular permutation and retain the same overall structure of the protein:
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1. What is an inverted protein?

An inverted protein is a type of protein that is synthesized in reverse order compared to the typical sequence of amino acids. This means that the amino acids are arranged in a reversed order, with the C-terminus at the beginning and the N-terminus at the end.

2. How is an inverted protein created?

An inverted protein can be created through various methods, such as chemical synthesis or genetic engineering. In chemical synthesis, the amino acids are assembled in reverse order, while in genetic engineering, the gene coding for the protein is manipulated to produce an inverted sequence.

3. What is the purpose of creating an inverted protein?

The purpose of creating an inverted protein is to study the effects of sequence on protein structure and function. By comparing the properties of the inverted protein to the normal protein, scientists can gain a better understanding of the role that sequence plays in protein structure and function.

4. How does the inverted sequence affect the protein's function?

The inverted sequence can significantly alter the protein's function, as it can affect the folding, stability, and interactions with other molecules. Inverted proteins may also have different enzymatic activities or binding capabilities compared to their normal counterparts.

5. Can an inverted protein be reversed back to its normal sequence?

Yes, an inverted protein can be reversed back to its normal sequence through a process called "re-inversion." This involves reversing the sequence of the inverted protein back to its original order using genetic engineering techniques. However, the re-inverted protein may not have the same properties as the original protein due to potential changes in the amino acid composition.

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