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 consuming proteins different vs. consuming amino-acids and how?

Yesterday I had a discussion with a friend. He said that consuming proteins and amino-acids is different. He said that those who grow muscles would agree on that. I wanted to argue against that ...
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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 with ...
6
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100 views

Proteins that are strongly overproduced in E. coli and S. cerevisiae?

I'm looking for some pointers to proteins that produce at really gigantic levels in E. coli and yeast (S. cerevisiae). Can anyone point to some champion proteins? Even in inclusion bodies and non ...
6
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123 views

Macromolecule levels in daughter cells after fission

When a prokaryote undergoes binary fission, how are the non-DNA macromolecules distributed between the two daughter cells? This is motivated by comments on a previous question and a G+ discussion. I ...
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How many different kinds of polypeptides, each composed of 12 amino acids, could be synthesized using the 20 common amino acids?

How many different kinds of polypeptides, each composed of 12 amino acids, could be synthesized using the 20 common amino acids? The book's answer is $20^{12}$. However, I disagree. This result ...
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What has caused life to choose this unfathomably tiny subset of all possible proteins?

I wonder why life uses the particular proteins that it does, about 10^6 different proteins, I think? Evolution cannot explain it because the number of possible proteins is far far too large to ever ...
5
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2answers
375 views

What does units/mg mean for Streptavidin

I got streptavidin for surface reaction. The label says "biotin binding: 16 units/mg". What does units/mg mean? Does it mean "1 mg biotin can bind to 16 units ...
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407 views

What medical and commercial proteins are made using genetically modified animals?

Recombinant technologies in micro-organisms being used to produce commercial and medically useful proteins like insulin are fairly common. However some proteins are still produced commercially in ...
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264 views

Protein structures given in PDB and SNP's

There are millions of proteins given in PDB, the sequence for which we can download in FASTA format. There are also hundreds of SNP's given in NCBI dbSNP. My question is whether the proteins in PDB ...
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How does protein denaturation work?

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

What are some examples of genes that code for multiple proteins?

The title pretty much says it all. It is widely taught that a gene in a eukaryotic system could produce more than one protein due to post-transcriptional modification, but I do not believe I have come ...
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Can proteins move outside cells?

I am trying to learn about basic cell biology, and have what is probably an extremely simple question. So this is how I understand it so far: Proteins are made from amino acids. This process is ...
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5answers
200 views

Why do asparagine and glutamine have two different abbreviations? [closed]

I'm looking at amino acid abbreviations and on every site I visit, asparagine and glutamine have two different abbreviations. Is there a reason for this? Do they represent different forms of the amino ...
5
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1answer
941 views

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 ...
5
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1answer
984 views

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 traversing ...
5
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1answer
2k views

How does the enzyme ATP Synthase use a proton concentration gradient to make ATP?

I understand what the enzyme ATP synthase does, but I'm not exactly sure how it does it. I've heard that it uses rotary catalysis, but how exactly does this work? How is the energy from the H+ ion ...
5
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323 views

When does oxidation destroy prions?

It seems like a no-brainer than oxidation, playing the, er, role it does in the universe, would destroy prions just like it destroys everything else. But when does it do that? I assume this has been ...
5
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What's the opposite of a thermophile?

Thermophiles, heat-loving organisms, have been a popular topic of research for decades due in large part to the utility of their enzymes in various chemical reactions (Taq Pol single-enzymedly made ...
5
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338 views

Lac operon: How can lactose enter the cell in the absence of lactose permease?

My textbook states that lactose permease...transports lactose into the cell and When lactose is added to the growth medium, the lactose molecules bind to the other site on the repressor ...
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168 views

Need some good resources to learn about Protein function and structure

I'm taking a course on biochemistry at edx. Since I'm a computer science student, I'm having some trouble in understanding many biochemical concepts. While the first module was just fine, I found the ...
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4answers
440 views

Any good website/book to understand protein folding and enzymes?

I'm looking for a good, understandable and simple explanation about protein folding, mechanisms and function, and their relationship with enzymes. I understand that the protein is a polypeptidic ...
5
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2answers
537 views

Why proteins are not visible on my membrane after ponceau staining?

I have a problem in western blot that I can't resolve by myself. When I am use to add 100 microgram of proteins for each sample but after running and transfer its impossible to me to see bands of ...
5
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1answer
742 views

What are the various types of protein-protein interactions

I understand there are a number of protein-protein interactions, but what types of interactions exist? and what are the characteristics of them?
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Are SLC52A2 and GPR172A really the same?

The official HUGO gene nomenclature page says that GPR172A (Gamma-hydroxybutyrate receptor) and SLC52A2 (riboflavin transporter, member 2) are the same. The sequence reported by Andriamampandry seems ...
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234 views

How are DNA polymerase error rates measured?

It is well known that the first DNA polymerase, Taq, is quite error prone. Newer generation commercial enzymes that have either been isolated from different thermophile species or have been improved ...
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151 views

Determining if a Protein Model Contains a Backbone Clash

I have an ensemble of homology models of a protein, and I now wish to remove those models which have backbone clashes. I could obviously check by eye but this is subjective and probably will not be ...
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40 views

Are all protein composed of all the amino acid (in animal) or are there less diverse protein?

I have a question about amino acid composition of proteins: Are there proteins in animals that are made up only from a small subset of amino acids? So instead of all 20 amino acids let's say only 6-14 ...
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598 views

What percentage of a cell's volume is occupied by protein?

I was looking at one of David Goodsell's illustrations of a cell: And it seems to suggest a very crowded picture of the intracellular environment. Just how crowded are cytoplasms? What percentage ...
5
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88 views

What is the advantage of the way eukaryotes initiate translation?

The eukaryote and prokaryote mechanism for translation is slightly different. Is there any advantage of the eukaryote translation mechanism ? Edit : I specifically want to know why eukaryotic ...
5
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409 views

Where can I find the tissue-specific protein expression levels for hTERT (telomerase subunit)?

I find a number of contradictory sources regarding the tissues in which hTERT - the protein - is expressed. Does anybody know some resource that authoritatively (as authoritative or widely-accepted as ...
5
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264 views

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 ...
5
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129 views

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 ...
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178 views

Mechanism of Muscle Growth

According to this video (sorry for the poor reference but it represents my level of understanding in physiology), muscle grow as a consequence of repairing micro-lesions. How are these micro-lesions ...
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129 views

Selective Androgen Receptor Agonist

I'm looking for an inducer that strongly activates the androgen receptor, but not the glucocorticoid receptor that is not DEA regulated. I know that SARMS (Selective Androgen Receptor Modulators) are ...
5
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54 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 ...
5
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65 views

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 that ...
4
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285 views

Amino acid compatibility

The (human) genetic code encodes 20 amino acids. They form a protein using peptide bonds. Each amino acid has a carboxyl group (COOH) and an amino group (NH2) that can potentially form a peptide bond. ...
4
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Are There Rules for How Proteins Are Formed?

Proteins are formed by stringing together different amino acids. Different amino acids have different properties (such as being attracted to or repelled by water, positively or negatively charged, ...
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100 views

Turning publicly available genome data into proteins

I'm a computer scientist who is starting to dabble with biology. My eventual goal is to model different kinds of cells with a computer program. As of right now, I'm just trying to take some smaller ...
4
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2answers
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Calculating Protein Concentration from Kilo Units (KU)

I am looking to purchase Pyruvate Kinase from the Sigma Website, they state the volume in Kilo Units (KU) i.e. 1, 5 or 25 KU. It also states there are 350-600 units / mg protein. Does this mean one ...
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107 views

How do proteins and genes participate in learning?

I am a computer scientist that studies biology and bioinformatics. In the last weeks, I have been trying to study new research directions, and I would like to deepen my knowledge on the role and ...
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184 views

What do “e” “-” “C” and “E” mean in this output?

I have given an input of this protein sequence: MEPVDPRLEPWKHPGSQPKTACTTCYCKKCCFHCQVCFTTKALGISYGRKKRRQRRRPPQGSQTHQVSLSKQPTSQPRGDPTGPKE from this website along ...
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Importance of Double Helix DNA Structure

Gene expression involves transcribing only one strand of DNA molecule. So i was wondering what are some biological advantages of the double stranded DNA?
4
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1answer
208 views

How to remove bad lanes in ImageJ Westernblot analysis

I use ImageJ to do an analysis of a Westernblot Image. If everything goes as wanted the workflow is fine. But if I do something wrong creating a lane there is no undo for a lane and also no way to ...
4
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106 views
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204 views

What Proteins Are Universal To All Life Forms?

According to National Geographic, there are 23 proteins that are common to all life forms: All species in all three domains share 23 universal proteins, though the proteins' DNA ...
4
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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 ...
4
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1answer
544 views

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 ...
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530 views

Western blotting questions?

everyone. I've just been introduced to the procedure of Western blotting from my reading, though I'm not entirely sure about some points. I'd appreciate it if someone could help me with this. What ...
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Why don't amino acids get linked in the functional groups of acidic and basic amino acids?

There are 'acidic' and 'basic' amino acids like aspartate and histidine. When protein is synthesized with those amino acids, what ensures that the to-be-assembled amino acids will not bond to the ...