Denaturation of Proteins

Major questions addressed:
What is the denaturation of a protein?

Can heat cause denaturation?

What are common proteins?

What happens if we boil an egg?

How can we identify curd formation?

Can we develop sensors for this?

1)What happens when we boil a egg:

Reference:
Now put your eggs in the pot, fill the pot with water, turn on the stove, and we can talk about denaturation. Denaturation is what happens when heat is applied to the eggs. Chemically, this is the process by which the chains of amino acids are changed from their original (or native) state. The heat coming from your stove denatures the protein by disrupting some of its bonds that held the molecule into shape. In the case of hard-boiled eggs, the proteins clump together and solidify, causing the egg white and yolk to harden.
https://www.nature.com/scitable/blog/scibytes/why_do_eggs_hardboil/

Globular Proteins
Globular proteins are named for their approximately spherical shapes and are the most abundant proteins in nature. The globular proteins exist in an enormous variety of three-dimensional structures. Nearly all globular proteins contain substantial numbers of α-helices and β-sheets folded into a compact structure that is stabilized by both polar and nonpolar interactions

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/globular-protein

Egg Protein
Egg proteins, which are distributed in both yolk and white (albumen), are nutritionally complete proteins containing all the essential amino-acids (EAA).

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/egg-protein
Albumin is a single chain protein with low molecular weight (66/5 kDa) which containing 585 amino acids. Overview of Albumin and Its Purification Methods - PMC.

2)some of the questions addressed
what is that common example of a protein
Hb
Where do Hb found
RBC
Where do RBC present
In blood
What is the composition of blood:
Plasma, also known as blood plasma, appears light-yellowish or straw-colored. It serves as the liquid base for whole blood. Whole blood minus erythrocytes (RBCs), leukocytes (WBCs), and thrombocytes (platelets) make up the plasma. Serum, sometimes mistakenly considered synonymous with plasma, consists of plasma without fibrinogen. Plasma contains 91% to 92% of water and 8% to 9% of solids. It mainly comprises of:

Coagulants, mainly fibrinogen, aid in blood clotting Plasma proteins, such as albumin and globulin, that help maintain the colloidal osmotic pressure at about 25 mmHg
Electrolytes like sodium, potassium, bicarbonate, chloride, and calcium help maintain blood pH Immunoglobulins help fight infection and various other small amounts of enzymes, hormones, and vitamins.

CUBE context to curriculum WhatsApp group discussions:

[06/10, 12:58 pm] Seethalakhmi: It doesn’t seem surprising??? :eyes::eyes:
What is the reason for hardening of egg& softening of potatoes while boiling???
Any comments?
@⁨Theertha⁩, @⁨Kiran , @⁨Sneha Maurya⁩, @⁨Sakshi⁩, @⁨Enas⁩, @⁨Himanshu Joshi⁩ , @⁨~Rishu Raj⁩, @⁨~˚ ༘♡ ⋆。˚Åм𝐢𝘴ʱ𝖆˚ ༘♡ ⋆。˚⁩,@⁨~M S Sailekshmi⁩, @⁨Chithra , @⁨Arunan And others?

[06/10, 1:11 pm] Vikram: I don’t know why the word surprising should be used.

One of these items is a vegetable, the other is a complex (two distinct regions) egg.

It would be surprising, in my opinion, if immersion in boiling water has the same effect.
[06/10, 1:14 pm] Arunan : Why do we think vegetables cannot harden, while boiling whereas, animal products harden on boiling? :upside_down_face::face_with_hand_over_mouth:

[06/10, 1:36 pm] Himanshu Joshi: Potato:
Heat breaks molecular bond within the cell wall

Egg:
Denaturation of both albumin and yolk proteins happens resulting in breakage of bonds between these proteins

In both processes molecular bonds are breaking then how potato softens and egg hardens?
[06/10, 1:56 pm] Vikram: Carbs soften whereas proteins harden to clump together? What will happen instead of water we choose say ammonia Or tri-isobutyl amines?
[06/10, 2:21 pm] Vikram: No, that is not correct. Heating, and particularly boiling in water, is used to soften meats. Possibly, the chemical reaction involves breaking down of protein fibres.

But breakdown of fibres is different from breakdown of molecules.

In this case, it is protein folding that is the key, dealing with the changes in relevant proteins thanks to the effect of boiling water
[06/10, 3:09 pm] Seethalakhmi: Sir, reference please
[06/10, 3:09 pm] Chithra : Egg proteins coagulate/clump and harden on heating because the non-covalent bonds/interactions such as the hydrogen bonds, hydrophobic interactions and ionic bonds are disrupted during heating and the three dimensional structure of proteins is lost making them clump together.
Milk proteins do not clump during heating/boiling because the sugars in milk stabilise the proteins.
Vegetables soften on cooking because the water in the vegetable heats and dissolves the pectin matrix joining the cells as well as holding the cellulose/ hemicellulose fibres leading to separation of cells and partial breakdown of the rigid walls. The turgidity of cells is also lost due to breakdown of cell membranes resulting in collapse of cells.

[06/10, 6:03 pm] Prathibha: Taking the case of sugars present in milk that helps in stabilizing the proteins and hence they do not form clumps, if we change the pH of milk for e.g. while making paneer n when we perform curdling of the milk, there is no sugar present in the milk that stabilizes it as they have been converted into acids n the proteins then tend to clump together forming paneer that is similar to the white part of the egg. Both the paneer and boiled egg do not get dissolved in water since the three dimensional structure of the proteins in both the cases have been denatured due to heat and change in pH.
[06/10, 6:20 pm] Chithra Ma’am: The sugars in milk can’t probably prevent denaturation of milk protein by change of pH on adding lemon or salt.

1 Like