Can a mutation change a protein's tertiary structure without changing its primary structure?

[calvin.gogo13]

So altius says if primary structure changes, without altering its AA (point mutation) this doesnt have to result in 2ndary or 3tiary changes which makes sense

Chegg.com

- So chegg says no, Tertiary structure changes must be caused by mutation of primary structure (change of amino acids)

- But I was thinking: How bout covalent bonding/hydrogen bondings/ionic interactions?

So do we assume that yes, TERTIARY changes MUST be due to AA/Primary structure changes?

With that being said, I'm guessing secondary and tertiary structure changes does NOT always result in quarternary structure change?

---

Members don't see this ad.

 

[Hopeful_Doc123]

From my understanding, any mutation that causes a downstream change (secondary/tertiary/quarternary) must stem from a primary structure change, and more specifically a genetic mutation in the DNA.

That being said, there are mutations that are less significant to (BUT STILL MAY CHANGE) tertiary structure (D-->E, L-->A, V-->I), as long as the properties of the AA remain somewhat conserved.

Hope this helps!

 

[StevenBrata]

How bout covalent bonding/hydrogen bondings/ionic interactions?

Is it because these came from Amino Acid Changes to begin with that they also change?

 

[Ad2b]

Not sure if I'm fully understanding your comment related to quaternary structure.

Quaternary structures are different structures from different chains closely packed together. So, 2 alpha + 2 beta = quaternary...

Primary, secondary and tertiary are ALL the same strand just folded in different ways upon itself.

 

[StevenBrata]

Not sure if I'm fully understanding your comment related to quaternary structure.

Quaternary structures are different structures from different chains closely packed together. So, 2 alpha + 2 beta = quaternary...

Primary, secondary and tertiary are ALL the same strand just folded in different ways upon itself.

So basically this is like the fact that Bananas are BERRIES and Strawberry are not BERRIES, but they both fall under a fruit.

Statement 1: A Change in primary structure CAN cause a change in 2ndary/3tiary/4ternary structures, but it DOES NOT have to.

Statement 2: A change in 3tiary structure MUST be caused by 1mary amino acid changes along with other interactions but it MUST include 1mary AA changes.
- this is the statement I'm iffy about because tertiary structures are formed through electrostatic interactions, etc so is this statement true or false?

 

[siliso]

How could next order structures, bindings, organizations change while the primary structure was still 100% same?

 

[Ad2b]

How could next order structures, bindings, organizations change while the primary structure was still 100% same?

Can't or it becomes a different structure - secondary or tertiary.

Primary is primary, a chain. Secondary, beta-sheets, are the primary chain folding onto itself; Tertiary are the interconvoluted mess that still comes from the same chain at start. Quaternary is different structures from different chains coming together.

 

[ultravioletcat]

So ****** says if primary structure changes, without altering its AA (point mutation) this doesnt have to result in 2ndary or 3tiary changes which makes sense

Chegg.com

- So chegg says no, Tertiary structure changes must be caused by mutation of primary structure (change of amino acids)

- But I was thinking: How bout covalent bonding/hydrogen bondings/ionic interactions?

So do we assume that yes, TERTIARY changes MUST be due to AA/Primary structure changes?

With that being said, I'm guessing secondary and tertiary structure changes does NOT always result in quarternary structure change?

Beta-mercaptoethanol can break disulfide bonds and thus unfold tertiary structure, though this is reversible. Urea can do something similar by disrupting H-bonds.

Tertiary structure is largely held together by non-covalent bonds. You don't need to break peptide bonds for there to be disruptions in tertiary structure.

 

[StevenBrata]

Can't or it becomes a different structure - secondary or tertiary.

Primary is primary, a chain. Secondary, beta-sheets, are the primary chain folding onto itself; Tertiary are the interconvoluted mess that still comes from the same chain at start. Quaternary is different structures from different chains coming together.

So is my second statement true?

 

[Ad2b]

So is my second statement true?

no, it is false

Think of a primary chain like a strand of beads (alpha). Fold it over onto itself and hold pieces together with toothpicks (beta sheet). Now, wind that around itself, somehow, and you have both a helix from alpha, and a beta from folding and it becomes a tertiary. Same strand, just different orientations and bonds holding it together.

No change in amino acids. No change in number of amino acids. No changes in order of amino acids.

If you were to unfold the whole tertiary, secondary you'd get the original primary strand in its exact form

Now, take 4 of those and put them together by different types of toothpicks/straws and you could have a heme which is the usually tested quaternary on the MCAT.

Ignore the exceptions or how this can be undone above me. Understand the concept first.

 

[StevenBrata]

no, it is false

Think of a primary chain like a strand of beads (alpha). Fold it over onto itself and hold pieces together with toothpicks (beta sheet). Now, wind that around itself, somehow, and you have both a helix from alpha, and a beta from folding and it becomes a tertiary. Same strand, just different orientations and bonds holding it together.

No change in amino acids. No change in number of amino acids. No changes in order of amino acids.

If you were to unfold the whole tertiary, secondary you'd get the original primary strand in its exact form

Now, take 4 of those and put them together by different types of toothpicks/straws and you could have a heme which is the usually tested quaternary on the MCAT.

Ignore the exceptions or how this can be undone above me. Understand the concept first.

If we reduce covalent bonds in a tertiary structure, that alone changes the structure without altering the primary structure right?
This is what you're trying to say how, tertiary structure do not always constitute a change in primary structure?

 

[Ad2b]

If we reduce covalent bonds in a tertiary structure, that alone changes the structure without altering the primary structure right?
This is what you're trying to say how, tertiary structure do not always constitute a change in primary structure?

Sort of. What I'm saying if that I make a strand of bead labeled

C-R-A-F-T-Y-M-N-W-A-D-G-E-R-S

That's primary structure

If the string folds back onto itself so that it looks something like:

C-R-A-F-T-Y-M-N-W-
............S-R-E-G-D-A

That's secondary structure (beta-sheet) even if it's not end to end

Now, if somehow a covalent bond forms between the M on the upper strand and the C on the upper strand, that is a covalent bond, specifically a disulfide bond (the sulfurs on both Methionine and Cysteine).

That "mess" - that blob that would form by the C folding and bonding with M - would be a tertiary structure.

Take 4 of those and you have quaternary structure (like heme).

The bonds between the C-N (peptide bond between amino acids) on the primary chain are very difficult to break. Therefore, the primary structure would remain intact.

Bond strength between those letter (beads in my original example representing amino acids) except for the Carbon-Nitrogen bonds are hydrogen bond, electrostatic bonds, etc and easily broken. If broken, the lettering order doesn't change, just the structure.

 

[PlsLetMeIn21]

Changing an amino acid changes the primary, secondary, and tertiary structures, we all seem to agree.

But changing the tertiary structure can be done by either (a) changing the primary sequence or (b) changing the environment such as moving the protein from a hydrophilic environment to a hydrophobic environment or adding a reagent like urea or beta-mercaptoethanol.