# Tag Info

### Can lipases cleave fatty acids linked with amides instead of the usual esters?

Yes they can, but they have higher specificity for esters. Here is part of the abstract of a paper using directed evolution to increase the activity: A double mutant F207S/A213D gave the highest ...
• 34.5k
Accepted

### Why do hydrogen bonds between atoms of the polypeptide backbone, form both helix and pleated structures, instead of only one structural type?

Proteins have segments of their polypeptide chain/chains that can be repeatedly coiled or folded into helix and pleated structures, respectively. This is due to hydrogen bonds between partially ...
• 34.5k
Accepted

### Are lipid membranes destabilized by aligning so many negatively charged phosphates in close proximity?

In a bilayer the charged head groups are in contact with the water and the fatty acid chains are in the middle of the bilayer. In water, bilayer formation is largely an entropic effect. In isolated ...
• 28.1k

### Why do hydrogen bonds between atoms of the polypeptide backbone, form both helix and pleated structures, instead of only one structural type?

I imagine this is largely determined by function. In a protein such as bacteriorhodopsin there are several parallel helices which hold the protein as a fairly rigid structure with a channel down the ...
• 28.1k

### Why do hydrogen bonds between atoms of the polypeptide backbone, form both helix and pleated structures, instead of only one structural type?

Particular protein structures arise because of a potentially very complex interplay of interactions within a chain, with other chains (from other subunits in a multimeric protein or from chaperones or ...
• 19.8k
1 vote

### Why are proteins made up of alpha amino acids and not beta amino acids?

Adding to Poutnik's useful answer, polyptides/proteins made of alpha-L-aminoacids are capable of participating in a number of secondary structures, such as alpha-helix, beta-pleated-sheet, &c. In ...
• 174

### Why are proteins made up of alpha amino acids and not beta amino acids?

Questions why? in context of various levels of life design are tricky and rather philosophical. Beta/gamma amino acids would not be optically active, neither (alternative) proteins formed from them. ...
• 32.4k
1 vote

### How to determine the charge of amino acid at certain pH?

The change of $\mathrm{pH}$ from $+1$ to $+2$ does not change much in the main formula of alanine, which is and stays $\ce{H3\overset{+}{N}−(CH3)CH−COOH}$, up to $2.34$ which is the first \$\mathrm{p}...
• 24.4k