Biopolymers consisting of amino acids that fold into 3D shapes and perform a large number of functions in living organisms.

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2answers
29 views

Why can't proteins make copies of themselves? [on hold]

Why is it impossible for proteins to make copies of themselves?
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1answer
26 views

Once in the membrane, why don't proteins move?

I understand that based on their tertiary structure, intrinsic proteins have Hydrophobic [polar] R - Groups on their Surface and that they 'interact with the hydrophobic core of the cell membrane to ...
1
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2answers
32 views

How do prions transmit their conformation to other proteins?

I was reading about prions and many sources say something to this effect: "Prions may propagate by transmitting their misfolded protein state: When a prion enters a healthy organism, it induces ...
0
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0answers
22 views

Which proteins cross the blood brain barrier?

Are there any known globular proteins which naturally cross the blood brain barrier as part of their function, i.e., without modification? I'm thinking not just human proteins, but also viral ...
1
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0answers
34 views

What is the most stable globular protein?

What is the most thermodynamically stable globular protein? I am looking for a small (ideally less than 50kDa) soluble globular protein motif which folds easily/reliably and is known to be extremely ...
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0answers
11 views

Alkali Biuret Test [closed]

In a Biuret test, the reagent is Copper (II) Sulfate in Sodium Hydroxide Solution as the Alkali. What is the purpose of the Alkali?
0
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1answer
22 views

Why have multiple alleles for beta chains evolved in certain parts of the world? [on hold]

I believe that this could be because individuals may have had interactions with a parasite, for example Malaria, that caused changes resulting in different beta chains. Can anyone explain this more ...
0
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0answers
17 views

Maintenance of muscle mass due to doping anabolic substance [closed]

Take the case of an athlete looking to increase his muscle mass, it will take anabolic doping substances during a certain period of time then it will stop. Is it possible for this athlete to maintain ...
1
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1answer
33 views

Does the order of amino acids matter in making up a protein?

For instance, if a protein is made of 2 amino acids, that is, AB, would the same protein form if the order of combination of amino acids become BA? If yes, would the behavior of interaction of that ...
3
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0answers
14 views

What are the secondary structure requirements for cell-penetrating peptides AKA protein transduction domains

Some background: Cell penetrating peptides (CPPs) are a class of short amino acid sequences which are sufficient for crossing cell membranes and delivering themselves along with any attached cargo ...
0
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0answers
50 views

Disease-Associations For Protein Analysis? [closed]

I would like to get access to any protein database of disease-associations which I could use home with biomechanical signals in different systems. A similar software to what I am looking for is the ...
0
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1answer
35 views

Relative concentration of enzyme vs reaction product

I was reading a paper in which a recombinant protein (His-6 tagged) is expressed in E Coli (BL21 DE3). The yield of the enzyme isolated from the culture is reported as 10-30 mg per L of bacterial ...
0
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0answers
21 views

Best protocol to optimize solubilization of bacterial fusion proteins?

I'm trying to produce an His-tagged protein in E.coli. Before performing the Ni-NTA column I need to figure out how to extract most of the protein from the cell pellet but I'm getting lost with a ...
2
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0answers
36 views

Structure of proteins

Regarding the secondary structure of proteins, I know that there are 3 main types. The beta sheet formation is made up of beta strands stabilized by hydrogen bonds to form an anti parallel or a ...
1
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1answer
23 views

Hydrophobic proteins in the body?

I know that we can get hydrophobic amino acids, but are there any proteins in the body whose surface is hydrophobic? If so what is their typical function and where can they typically be found and if ...
0
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1answer
71 views

If human proteins are synthesized from only 20 different amino acids, then how can there be such variety of proteins in human cells?

I know that human proteins are synthesized using only 20 different amino acids. However, how can there be thousands of different proteins in human cells, if we only use 20 amino acids to make them?
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4answers
149 views

Do all cells produce the same proteins?

If DNA is more or less the same in all cells, and DNA is used to produce proteins from aminoacids, then do all cells produce the same proteins or are they specialised/controlled by something?
1
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0answers
26 views

How accurate are proteomic-based biomarkers of cancer? [closed]

Currently protein expression is one of the widely used biomarker types. For example, any $i^{th}$ protein could be a selected biomarker. How can a minute change in single protein concentration ...
2
votes
2answers
26 views

How to obtain a list of proteins sorted by the ~1400 unique protein folds?

The databases CATH and SCOP both have around 1400 unique protein folds recorded from analysis of the PDB. However, I do not see any method to access this particular data. A list of each of the 1400 ...
1
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0answers
24 views

Can aptamers be used to identify the terminal amino acid residue of a peptide?

Suppose there were DNA or RNA aptamers that bind specifically to a certain terminal amino acid residue. Let's name it aaSA (amino acid specific aptamer). For example, the aptamer binding to terminal ...
0
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0answers
21 views

How does Ultra-pasteurized milk compare with pasteurized milk?

I am specifically interested in whether all proteins and nutrients lose their structure permanently because of the very high temperature of ultra-pasteurization. What is the case for pasteurized ...
4
votes
1answer
56 views

How to get the correct RefSeq Protein transcript for a given RefSeq Nucleotide transcript?

How to get versioned Protein Accession Number for a Refseq Accession Number? I have some versioned RefSeq Accession numbers and I would like to know their corresponding Protein Accession Numbers. ...
2
votes
1answer
42 views

Server for protein structure prediction for multiple sequences

Does anybody have any idea about any online server that takes in multiple amino acid sequences in fasta format and outputs the 3D structure of the input amino acid sequences in the form of helix, ...
3
votes
1answer
91 views

What is an isolated beta bridge?

DSSP gives the letter B for a "residue in isolated β-bridge (single pair β-sheet hydrogen bond formation)", according to Wikipedias page for secondary structure (and various other proper sources). Can ...
4
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0answers
29 views

Derivation of Michaelis' Equation from Michaelis' Constants [duplicate]

The enzyme reaction condition, $E + S \leftrightarrow ES \rightarrow E + P$ uses $\kappa_{1}$ (forward reaction), $\kappa_{-1}$ and $\kappa_{2}$ as the rate constants. E: Enzyme S: Substrate P: ...
1
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1answer
22 views

What are in common between transcription factors?

In terms of their structures (primary to tertiary) and locations? Why do they have these commonalities? Or are any of these commonalities critical to their functions?
4
votes
1answer
73 views

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 all ...
3
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1answer
62 views

What is the lower temperature limit for ion channels function?

What is the cold-block temperature of ion channels? (not of nerves or axons)
0
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1answer
44 views

A molecular marker for global protein synthesis

I know that protein synthesis is governed by a lot of factors (I'm mostly studying the mTOR pathway), but I'm looking for some kind of marker that will indicate the global protein synthesis rates. I ...
5
votes
1answer
53 views

Electrophoresis of hemoglobin from a carrier for sickle cell anemia shows two bands - why not three?

Electrophoresis of hemoglobin from a carrier for sickle cell anemia shows two bands - why not three? Since there are two beta chains in each hemoglobin, it seems to me they should have three types of ...
0
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0answers
29 views

How hydrophilic is human mucus?

I am interested in the stability of virus particles in human mucus, and how this may bias the evolution of surface amino acids in respiratory viruses. For instance if the mucus environment were more ...
10
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2answers
133 views

Protein tertiary Structure formation

As we know that coils and loops are evolutionary variable regions where mutations,deletions, and insertions frequently occur. So does it mean that they don't have much role in the structure of ...
0
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1answer
58 views

Predicting 3D structure of a protein?

While predicting 3D structure of a protein through homology modeling, the most important step is Multiple Sequence Alignment of template sequences with the target protein whose 3D model is to be ...
0
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0answers
10 views

Are receptors integral membrane proteins or peripheral membrane proteins?

In tegral membranes serve as transporters. Peripheral protiens serve as cell adhesion molecules, antigens and enzymes. So what about receptors? Which protiens carry out the duty of receptors?
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0answers
25 views

mRNA extraction from mice ears.

I am trying to extract RNA from mice ears and for some reason I don't have RNA when I perform the electrophoresis. I directly cut the ears and I put it in a tube with a bead and trizol. then I place ...
2
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0answers
27 views

Lifeforms concentrations of the categories of macromolecules, and Lipids

Lifeforms are formed of large, modular, organic molecules called macromolecules, large organic molecules called Lipids, and simpler molecules such as H2O. Macromolecules are commonly grouped into the ...
0
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1answer
30 views

How does protein enter bloodstream?

If a hemophiliac patient injects his factor 8 through the veins directly into the bloodstream to provide the body with clotting factor... Why don't they just make the drug as a pill and have the liver ...
0
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1answer
43 views

Will dissolved proteins pass through a 0.2 micron filter?

Given that there may be exceptions, can you usually expect protein to pass through?
2
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1answer
60 views

Why does heating kidney beans at a low temperature potentiate the toxicity of phytohaemagglutinin?

I recently found out that red kidney beans contain a relatively high amount of the toxic lectin, phytohaemagglutinin. An article on phytohaemagglutinin on the FDA website states: Several ...
0
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0answers
8 views

Is there a deblocking aminopeptidase without normal aminopeptidase activity?

The deblocking aminopeptidase is a unique exo-type aminopeptidase that liberates blocking groups (formyl, acetyl, and myristyl) from proteins and peptides. However, according to this paper, it has two ...
1
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0answers
52 views

Which of the three is true for insulin receptors?

I have seen the following question in a Cell Biology exam: Which of the following is true" Insulin has an hydrophobic Signal Peptide and the insulin receptor does not have an hydrophobic ...
0
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1answer
56 views

Why do raw prawns turn red after sitting in vinegar?

Yesterday morning I put some raw prawns (shell removed) into vinegar (more specific this one), and put them in fridge. When I came back at night all of them turned red, which looks cooked, except ...
0
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0answers
20 views

SDS-Page-Concentration confusion

So I purified some a protein, purified it using two different types of resins (comparing resins for cost efficiency). Ran a Bradford Assay to find concentrations of each. Unsure of SDS-Page protocol ...
2
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1answer
51 views

How do proteins perform their function [closed]

I have asked a question on physics stackexchange, but was redirected here. I copy the entire question word for word. The original is here. Let's, for example, take a ribosome. It is an enzyme that ...
1
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1answer
28 views

A question involving immunoprecipitation to identify interacting proteins?

Using recombinant Flag-tagged Dcr-2 and His-tagged protein X, pull-down assays were performed to determine whether protein X and Dcr-2 interact directly. The recombinant proteins (either alone or in ...
1
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0answers
11 views

Which fractions are enriched for siRNA cleavage activity by comparing electrophoresis?

Size exclusion column chromatography was used to separate the proteins in a Drosophila cell lysate to attempt to identify the protein complex responsible for processing long dsRNA into siRNAs. ...
3
votes
1answer
94 views

Does urea at different concentrations (5 or 0.5M) have different effects on proteins?

The problem is to explain why each additive gives rise to the distribution of the protein (RMAS) as shown in the Western blow below: In each case, the homogenates were subjected to high-speed ...
3
votes
1answer
46 views

Resolution of X-ray crystallography

A structure determined by X-ray crystallography has a resolution of 1.5 Å. When I look at the coordinates, I find every backbone C-N distance is 1.32 Å.i.e. Accurately predicted. If resolution is not ...
1
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1answer
42 views

Stabilizing forces between the protein sequences?

we know that Protein structures from secondary to Quaternary are maintained by noncovalent or weak interactions including electrostatic interactions,van der Waals forces & hydrogen bonding. What ...
2
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1answer
466 views

Difference between protein channels, protein carriers and protein pumps?

I'm revising for my biology exam and I don't fully comprehend the difference between protein channels, carriers and pumps. I know that: Protein channels do not require ATP (passive transport) The ...