Does high pH values break H bonds of a protein or just the ionic bonds?

Question

explain if possible. thanks

Answer 1

At physiological pH most of the -COOH of amino acids are deprotonated (-COO-) and -NH2 protonated (-NH3+).
If you increase the pH then the -COO- will remain as such but the -NH3+ will lose the proton. -NH3+ can act only as an H-donor for an H-bond so such a bond will be broken. However if the geometry and number of interacting partners allow it it could be replaced by another H of the same -NH2 group.

Tyrosine has pKa around 10, so if you go to extremely basic pH it will be deprotonated and thus it will not be able to act anymore as an H-donor for a hydrogen bond and the bond will break. If however it was acting as a lone pair donor, the bond will become even stronger.

Generally when the pH change (extremely basic or acidic) causes changes in the charge of the group can but not necessarily breaks H-bonds. An important note: even if the H-bonds are not completely broken there will be rearrangement (some bonds might break and others form as the some H-donors become H-acceptors and vice versa) changing the conformation/folding of the protein.

For sure the effect of pH on ionic bonds is far greater than that on H-bonds.

Answer 2

a High pH value means its rather basic so yes the it can cause the polypeptide to change shape. Both heat and pH level affect different structures at different levels but the teriary structure is particularly affected by these changes causing denaturization. the hydrogen bonds and polar attraction all affect the shape of the protein at the tertiary level and are changed with pH and heat

Answer 3

Covalent Bonds-Covalent bonding is a style of chemical bonding between 2 non steel atoms that's characterised by making use of the sharing of pairs of electrons between atoms and different covalent bonds. A covalent bond is formed between 2 non-metals that have comparable electronegativities. Neither atom is "sturdy" sufficient to entice electrons from the different. For stabilization, they share their electrons from outer molecular orbit with others Ionic Bonds-Ionic bond, additionally ordinary as electrovalent bond is a style of bond formed from the electrostatic allure between oppositely charged ions in a chemical compound. a number of those bonds happen particularly between a steel and a non steel atom. An ionic bond is formed between a steel and a non-steel. Non-metals(-ve ion) are "greater suitable" than the steel(+ve ion) and would get electrons very rather from the steel. those 2 contrary ions entice one yet another and grace the ionic bond. EG: Covalent: Methane (CH4), Hydro Chloric acid (HCL), which components are all nonmetals Ionic: Sodium chloride (NaCl), Sulphuric Acid (H2SO4 ) etc.

Answer 4

High pH values affect the protein structure in more than one level, producing denaturation.

Here is a fragment from the article on Denaturation from wikipedia:

In quaternary structure denaturation, protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted.

Tertiary structure denaturion involves the disruption of:

- Covalent interactions between amino acid side chains (such as disulfide bridges between cysteine groups)

- Noncovalent dipole-dipole interactions between polar amino acid side chains (and the surrounding solvent)

- Van der Waals (induced dipole) interactions between nonpolar amino acid side chains.

In secondary structure denaturation, proteins lose all regular repeating patterns such as alpha-helixes and beta-pleated sheets, and adopt a random coil configuration.

Primary structure, such as the sequence of amino acids held together by covalent peptide bonds, is not disrupted by denaturation.

Answer 5

high ph(12.4) value can break h-bonds in DNA