28 Answered Questions for the topic Proteins


Are quaternary protein monomers unique to a particular protein complex?

I know that quaternary protein structures are formed exclusively via non-covalent bonds. My biochemistry professor discussed a viral capsid that is essentially one quaternary structure with 240... more

How can I differentiate between polysaccharide bands and protein bands on SDS-PAGE?

I tried to extract bacterial polysaccharide but after running a SDS-PAGE I couldn't differentiate between the polysaccharide band and protein ones. I face a problem of moving up of the samples from... more

Do chaperone proteins misfold?

If molecular chaperone proteins assist in the folding process of other proteins and misfolded proteins, can chaperone themselves misfold since they are also proteins? What would happen if... more
Proteins Biochemistry


Is there a difference between polarity and hydrophobicity?

From literature the two terms seem to be interchangeable when discussing protein domains and motifs. But biochemically, what are the specific differences between these two terms? For example what... more

What is the difference between a protein and a factor?

In terms of nomenclature/semantics, why are some proteins named proteins, and some named factors?I've been revising on eukaryotic DNA, and I've come across some proteins that seem to serve roughly... more
Proteins Biochemistry


Why is absorbance at 280 nm for protein solution going up when I measure repeatedly?

I have been measuring my protein solutions' concentrations by diluting them in water 20 fold with a final volume of 100 uL and then measuring the absorbances of these solutions in 96 well plates... more


What is an aromatic cage and what does it do?

Epigenetics, 2. ed, Chapter 3.6:> Similarly, methylated lysine residues embedded in histone tails can be> read by “aromatic cages” present in chromodomains, or similar domains> (e.g., MBT,... more


Why is glycine considered a nonpolar amino acid but a polar molecule?

Glycine has a dipole moment, so why is it considered a nonpolar amino acid when discussing its occurrence in proteins?Also, is the backbone of a protein nonpolar?
Proteins Biochemistry


Is ATP Synthase a channel or an enzymatic protein?

Today in a biology lecture about plasma membranes and functions of proteins, we learned about channel and enzymatic proteins along other kinds of proteins. ATP synthase is considered an enzyme that... more


Why are proteins always made in N to C direction?​?

Why are proteins always synthesized from the *N*-terminus to the *C*-terminus? Can there be any “reverse” peptide-bond formation to synthesize proteins in the *C*-terminal to the *N*-terminal... more


How does hypochlorous acid inactivate viruses?

I was reading how bleach was used very widely as a disinfecting agent during the 2014 West Africa ebola outbreak and am interested in the mechanisms with which hypochlorous acid inactivates... more


Is it possible to isolate and analyse intermediates of protein folding?

I would like to know if there is an assay which could allow us to analyse a protein before it has assumed its 3D functional form.While studying structural biology, I only came to know the forces... more


Why is leucine amino acid used the most in proteins and tryptophan the least?

The amino acid leucine, is used in proteins more than others. Leucine with 9.1 percent (its average in more than 1.150 different proteins) is used most and tryptophan with 1.4 percent is used less... more

Why don't membrane proteins move?

I understand that based on their tertiary structure, intrinsic proteins have hydrophobic non-polar R-groups on their surface and that they 'interact with the hydrophobic core of the cell membrane... more
Proteins Biochemistry


What is the process of degradation of proteins into amino acids inside living cells?

Just like beta oxidation does our cells have a distinct mechanism for degradation of proteins? There are processes for degradation of amino acids but where does these amino acids come from, is it... more

Is tyrosine hydrophobic or hydrophilic?

I’ve seen tyrosine classified as a hydrophobic amino acid due to its aromatic ring in some textbooks and as hydrophilic due to its hydroxyl group in other textbooks. How does tyrosine actually... more
Proteins Biochemistry


How does protein denaturation work?

I was wondering how protein denaturation works.1. Are there covalent bonds, such as disulfide bridges involved, or is it based purely on non-covalent bonds such as hydrogen bonds? Why is... more


Where do amino acids get attached to tRNA and where is it synthesized?

Some very basic parts of transcription/translation seem to be left out in various literature. I can't find the answer to this anywhere:How exactly is tRNA synthesized? I realize that mRNA is... more


How can a polar molecule pass through polar channels of proteins in the cell membrane?

To transport a polar molecule through the nonpolar cell membrane, a protein with a polar channel is needed to allow it to diffuse. However, if the molecule is polar and the channel is polar,... more


How do cells relocate transmembrane proteins from one side of the cell to the other? Is it possible?

Is there a process by which cells can relocate proteins residing on the cell membrane in areas of low demand to that of a high demand location somewhere else in on the cell? What's that process... more


If proteins have an overall charge, how do membrane proteins traverse through the hydrophobic region of the plasma membrane?

These two concepts seem almost contradictory, proteins have a net negative charge due to the amino acids in them each having a small negative charge, yet membrane proteins are able to exist... more

Non-ribosomal peptide synthesis: why Glutathione cannot be produced by the ribosome?

**Case**: I am writing a summary for a class in protein structure and function, and was asked to describe some different ways that peptides are synthesized (that does not involve the ribosome). I... more


What are some (bioinformatic) methods to characterize potentially novel gene transcripts?

I am working with a few novel transcripts of genes- before I confirm their existence experimentally, I would like to perform some bioinformatic analysis. I have already considered coding potential,... more
Proteins Pharmacology Cancer


Difficulty in finding protein inhibition drugs?

I was reading an article on a recent identification of a PARP-14 protein in cancer cells that is responsible for production of additional glucose which keeps cancer cells from dying, and that a... more


Where, on the mRNA coding for such a protein, would the ER signal sequence likely be located?

A. The signal sequence is not part of the mRNA and is added separately by an enzyme.B.Immediately before the stop codon.C. Anywhere in the mRNA.D.Immediately after the start codon.

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