Questions tagged [proteins]

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

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Is it scientifically feasible to compare two samples of different sizes, while values in each sample are average numbers?

I want to compare result from my protein docking experiments to various protein structures of the same protein. I have two samples and in Sample 1, I have ...
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Can enzymes be modeled using classical mechanics?

When enzymes interact with substrates (i.e. a small ADP molecule and the much larger ATP synthase), does quantum mechanics play a significant role? Or can the interactions be relatively accurately be ...
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Why is sickle cell trait expressed in half of all cells rather than all cells containing half-sickled haemoglobin

If sickle cell trait is due to be heterozygous with respect to a single gene mutation on the haemoglobin β-globin chain, why is it the case that ~50% of RBCs are sickled rather than half of the ...
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Fluorescence assays to identify protein concentration without adding a large peptide sequence?

I'm trying to find a way of tagging a protein with something visually quantifiable to track protein concentration through potential purification steps and screen for the most efficient such steps. ...
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Why does protein folding not depend on the order in which it is synthesized?

I read an article recently, written by researcher from Department of Biochemistry, University of Washington, which stated that: Similarly, success in de novo protein design bears on the question I ...
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How do mutations and protein synthesis link to cancer?

How do mutations and protein synthesis link to cancer? I know that a mutation in DNA can cause the triplet code on the mRNA to change so different amini acids are made and a different order means a ...
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Which proteins are most sensitive to electric fields?

Many Proteins have ionic charges that can attract each other (e.g. Formation of salt bridges) or repel each other. On the other Hand, Proteins are mostly immersed in water that screens most of the ...
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Biochemistry, Biology Thought Questions

Many proteins that regulate cell growth can be turned on and off. Frequently these proteins will be active when a particular serine residue has a phosphate group attached to its hydroxyl group and in ...
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40 views

Are there any proteins not found in the brain that are affected by prions?

A prion is an abnormally folded protein that is capable of causing otherwise normal proteins to also misfold and become prions. They are responsible for causing diseases such as Kuru and Creutzfeldt–...
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67 views

Why spider's web don't burn when electricity touches it?

I saw and spider on it's web at an electrical cable and thinked: If the web is made of proteins, why dont burn. Sorry, the photo is dark because is night in Ecuador
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Formation of disulfide bonds in protein expressed after transduction

Say I transduce a nucleic acid sequence using a viral vector that encodes a protein having at least one disulfide linkage. For simplicity, let’s assume that there are only two cysteines in the protein ...
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What is the typical range of volumetric productivity and cell density in aerobic fermentor bioreactors for microes?

Im doing research on biomass production. Its hard to find data for this question. I need citations to calculate the production rate of microbial biomass in bioreactors (e.g aerated fermentator). ...
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Estimating diffusion constant of a protein based on number of amino acids

Is there a way to estimate the diffusion constant of a protein based on the number of amino acids it is comprised of. I know that the shape of the protein has an influence on the diffusion constant, ...
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Do all humans have an identical nucleotide sequence for certain proteins, e.g haemoglobin?

All humans have the same sort of proteins in our bodies. Take haemoglobin for example. Is the gene coding for haemoglobin in my body identical to everyone else's gene or is there slight variations ...
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The Collagen Triple Helix

In the amino acid sequence X-Hyp-Gly (where X can be any amino acid) of the triple helix can the Hyp residue be both hydroxyproline and hydroxylysine? In our textbook it says that the Hyp residue is ...
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1answer
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Does the arrangement of amino acids in a protein matter for nutrition?

Let's say there are two diets, consisting of entirely different proteins. If you split up all of the proteins from one day of each diet, you'll get the same set of amino acids and the same count of ...
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What is the difference between protein and peptide? [closed]

On which basis do protein and peptide are divided? I mean which factors differentiate them?
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Why is sorbitol used in buffers?

Many protocols in my lab use sorbitol in buffers. For instance, in co-immunoprecipitation, we include it at a final concentration of 200 mM in our lysis buffer. I'm not entirely sure why though. I ...
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what is the relation between protein domain and disease? [closed]

I am computer science student, and I am interested in bioinformatics. Thus, I am just at the beginning of learning some biology concepts. I am asking about the relation between protein domains and ...
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1answer
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Is the chitin in an insect's exoskeleton cross-linked?

This answer to the question How to clean and preserve a cicada's molted exoskeleton (exuvia)? states: The exuvia is made of cross-liked chitin, and will not decay. You don't need any special ...
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1answer
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Lysozyme amino acid sequence: N-terminal extension

I looked up the amino acid sequence of lysozyme here: http://www.biology-pages.info/L/Lysozyme.html Then I crossed referenced that with the lysozyme sequence on UniProt: https://www.uniprot.org/...
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What is the function of spongin in sea sponges?

Sea sponges (Porifera) use different types of skeletons to support their structures. Some skeletons are built from minerals, some are built from proteins like spongin, and some use both. My question ...
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Can denatured GFP show fluorescence?

GFP ( green fluorescent protein) can show green fluorescence. And its fluorescence is due to the tri peptide chromophore which is given in below I was wondering, can we observe fluorescence, if we ...
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Why does it matter to predict protein structure?

And how do you predict it ? What is your input data (sequence of amino acids, temperature, pH, ...) ? Is there a "standardized" input that scientists agree on ? Moreover, I've read that knowing the ...
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Relationship between Communication Proteins and Gap Junctions

What is the relation between communication proteins and gap junctions? Do the communication proteins make up gap junctions or something?
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What is the subcellular location of synthesis of non-essential amino-acids?

What is location of non-essential amino acids synthesis in a cell? Is it some specific organelle? And what is the gene driver behind this? I thought the whole point of DNA is coding for how to ...
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How can I get the yield of my purified immunoglobulins?

In order to get the yield of IgY through a set of purification steps, what method can I use? Thanks in advice!
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How can I change my buffer system for protein purification?

I have a protein that I purified in PBS buffer, pH 7. I will do dialysis to remove salt and will then further purify the protein with ion exchange chromatography. I will need to use another buffer (...
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What buffer should I choose for IEX chromatography for purifying IgY

I will use ion exchange chromatography with an anion exchange column to purify chicken IgY. Prior to this I did dialysis to remove salts from previous purification steps, is it possible after this ...
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49 views

What does “count in gene set” mean?

I am trying to understand the analysis generated by STRING. In analysis for biological processes table, there is a column titled "count in gene set." This gives a value for example "68 of 498". What ...
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What is the relationship between Ca- and Na-ions and mucins and why?

According to Wikipedia https://en.wikipedia.org/wiki/Mucin#Secretion mucins (Proteins that form mucus) obtain viscoelastic properties by the Exchange of sodium and Calcium Ions. What is Happening ...
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Why does the ratio type III collagen:type I collagen increase after a tendon injury?

I read on {1}: Type III collagen has accumulated at the rupture site [of human Achilles tendon] probably due to microtraumas and the subsequent healing process. […] The increased content of type ...
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How are multiples transmembrane proteins translocated or embedded in the membrane?

This image is in the textbook, Molecular Biology of the Cell. I understand why the start and stop transfer sequences must alternate, but why is there 2 consecutive start transfer sequences at the N ...
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Genes of the electron transport chain

Where are the genes of proteins that make the electron transport chain of mitochondria?(are they in in the nucleus or they are in the dna of the mitochondria itself?) Thanks for this answering system ...
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conversion of distance matrices to pdb/coordinates

I am currently facing two transformational issues. Suppose I am given a protein's residue sequence and calpha distance matrix; is there a way to generate the 3d coordinates of the protein's residues ...
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Why do protein solutions have to be alkalised in biuret test?

I’ve read that CuSO4 solution reacts with peptide bonds that connect amino acids to create a violet colour, but the instructions always tell me to add NaOH solution to the protein solution before I ...
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229 views

How do organophosphates actually work?

The common explanation as to what the primary mechanism of action for organophosphates (and carbamates) is is the inhibition of the enzyme acetylcholinesterase and resulting buildup of acetylcholine ...
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Immunoprecipitation compared to western blotting

Immunoprecipitation and western blotting are both used to locate a specific protein within a sample and to isolate it. In immunoprecipitation, a specific antibody and agarose beads ( or other ...
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Preparing sample for SDS PAGE

I have more than 10 cell lysate samples (70 µL each) whose concentration varies from 1.9 mg/mL to 4.8 mg/mL. I have 5X and 2X SDS sample buffers. I would like to prepare SDS PAGE samples in such a way ...
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Why are prions in animal diets not destroyed by the digestive system?

According to CBC: Mad cow disease is the common name for a condition known technically as bovine spongiform encephalopathy, or BSE. [...] The only known source of mad cow disease is from animal-...
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Where can I find and download HMMTOP training set?

I would like to perform redundancy reduction for my test set for membrane topology prediction. I checked the 1998 paper and website of the HMMTOP server but haven't found any download links for the ...
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Backbone hydrogen bonds between adjacent amino acids in a protein?

Is it possible for two adjacent amino acids in a peptide to form hydrogen bonds between the backbone NH and CO? Are there any examples of such situations in proteins and how common are they? If ...
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Intein Splicing

Currently I am trying to read and understand this paper on intein splicing. https://sci-hub.tw/https://www.ncbi.nlm.nih.gov/pubmed/22001202 However, I'm a little confused with Figure 4. Why do the ...
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86 views

Does digestion require hydrochloric acid?

Would our digestion function any differently if we secreted something else, like sulfuric or nitric acid, instead? I'd assume an acidic environment may be required, but not sure if chloride is also ...
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If overcooked hard boiled eggs show these green sulfide rings, why do scrambled/fried eggs not show this?

In the image above, the dark green rings are ferrous sulfide rings, caused when the sulfur from the egg white reacts with the iron in the egg yolk when the egg is overcooked. I was wondering, given ...
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How do you interpret the resulting bands of gel zymography?

I would like to clear up some things for gel zymography. I understand that bright bands show proteolytic activity. But which molecular weight do these bands correspond to? Is it the weight of the ...
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How does the immune system recognize harmful proteins?

How does the human immune system detect whether a protein happens to be a protein found in the body that is supposed to be there, a bacterial toxin that should be inactivated, an already inactivated ...
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What is a secretion target family protein?

I came across this link: https://www.genome.jp/dbget-bin/www_bget?btw:BF38_3398 What is this protein, is it a secreted effector protein or is it something else? What is the difference between type ...
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Are there only a few alleles or groups of many alleles impacting protein structure and function?

I'm in the first year of Medicine and I'm studying Genetics and Evolution. I have this doubt in the back of my mind and I'm not being able to move forward without someone explaining me what's wrong ...
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How does the body detect irreversible binding to receptors?

I have read an article on Wikipedia about irreversible agonists and antagonists. These permanently bind to a target receptor on a cell. However, the receptor protein is then internalized and recycled ...