The structure of protein that is unaffected by heating is

Insulin is a globular proteins.

For stabilization of a - helix structure of protein, H-bonding is responsible which is in between  group present in protein.

In proteins, the secondary structure (such as α-helices and β-sheets) is stabilized by hydrogen bonds formed between the carbonyl oxygen of one peptide bond and the amide hydrogen of another.

CH? (methane) is produced / generated from paddy fields. And methane leads to both global warming and photochemical smog.

CO? is used in photosynthesis, acid rain etc. but methane is not consumed.

So methane is a stronger global warming gas than CO?

Linear: N? (azide ion)

Bent-shape: O? (ozone), NO? (nitrite ion), Cl? O (dichlorine monoxide)