This is the most underrated concept in protein folding. The secondary structure is still slightly more important, but zooming in on hydrophobic bonds gives a completely different perspective.
The distance of a bond says everything. Nitrogen and polar hydrogen are ~2 angstroms away from each other. That's very close. Yet, the distance of the 29 non-polar bonds in this image aren't much farther than that.
No bond is more than 2.7 angstroms away. Polar bonds of this distance are considered part of the hydrogen bond if they are part of a similarly tightly knit sequence. This upper bound is common at the ends of the secondary structure.
The main thing that indicates hydrophobic bonds are weaker than hydrogen bonds is that hydrophobic bonds are loosely connected. Hydrophobic bonds are more entropically favorable than hydrogen bonds though. Meaning, the residues that are part of hydrophobic bonds have a much greater free range of movement than residues that are part of hydrogen bonds.
Another thing to consider is that the hydrophilic residues are on the exterior because they have a greater attraction to water than the hydrophobic residues in the interior. Technically, all residues are hydrophilic, but some are more hydrophilic than others.
There is a theory called "hydrophobic collapse." This probably shouldn't be used, because the term "collapse" misleadingly implies that hydrophobic bonds are the most causally significant. They only have one thing going for them, they're entropically favorable. The term "entropy" and "collapse" are inconsistent with each other. The term "collapse" implies a restriction of free movement. The term "entropy" implies a greater free range of movement.
The reason why hydrogen bonds are more causally relevant than hydrophobic bonds is because they're denser and there are more of them. Not only are two hydrogen bonds closer to each other than hydrophobic bonds, but more importantly, long sequences form hydrogen bonds without interruption.
The distance of a bond says everything. Nitrogen and polar hydrogen are ~2 angstroms away from each other. That's very close. Yet, the distance of the 29 non-polar bonds in this image aren't much farther than that.
No bond is more than 2.7 angstroms away. Polar bonds of this distance are considered part of the hydrogen bond if they are part of a similarly tightly knit sequence. This upper bound is common at the ends of the secondary structure.
The main thing that indicates hydrophobic bonds are weaker than hydrogen bonds is that hydrophobic bonds are loosely connected. Hydrophobic bonds are more entropically favorable than hydrogen bonds though. Meaning, the residues that are part of hydrophobic bonds have a much greater free range of movement than residues that are part of hydrogen bonds.
Another thing to consider is that the hydrophilic residues are on the exterior because they have a greater attraction to water than the hydrophobic residues in the interior. Technically, all residues are hydrophilic, but some are more hydrophilic than others.
There is a theory called "hydrophobic collapse." This probably shouldn't be used, because the term "collapse" misleadingly implies that hydrophobic bonds are the most causally significant. They only have one thing going for them, they're entropically favorable. The term "entropy" and "collapse" are inconsistent with each other. The term "collapse" implies a restriction of free movement. The term "entropy" implies a greater free range of movement.
The reason why hydrogen bonds are more causally relevant than hydrophobic bonds is because they're denser and there are more of them. Not only are two hydrogen bonds closer to each other than hydrophobic bonds, but more importantly, long sequences form hydrogen bonds without interruption.
