Amino-acids are organic acids with an amino group in the alpha position (alpha-acids). They are the structural units of proteins and involved in many biochemical pathways.
Questions tagged [amino-acids]
165 questions
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How are amino acids neutral at physiological pH?
Amino acids with non‐ionizable side chains are zwitterions when they are at physiological pH, pH 7.4. This is what my book says. But I do not understand why. The Pka for a carboxyl group is around 3 and the pKa for an amino group is around 9. So the…
Cyrus
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Confusion on polarity and hydrophobicity of Proline, Tyrosine and Cysteine?
I will list here several sources that state differently on the polarity and hydrophobicity of Proline and Tyrosine:
From the article Amino Acid on Wikipedia, it states that Proline is a special case, Tyrosine is hydrophobic and Cysteine is also a…
Brainchild Ho
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How do you calculate or predict the charge of a protein at pH 7?
How do you calculate or predict the charge of a protein at pH 7 given a fasta sequence?
Any papers or online servers to do this is well appreciated.
VanJeer
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Which amino acids can be phosphorylated?
Definitely serine, tyrosine, and threonine. What about aspartate and glutamate? I thought the O- on the carboxylic acid side group could be phosphorylated but am getting mixed responses to this. Any thoughts / any other amino acids I'm missing?
Ally
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Protein function and how it does not get affected with amino acid
How is it possible that a protein's function is not changed when an amino acid within it is replaced?
Toni
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Identifying whether amino acids are hydrophobic or hydrophillic
How do you figure out whether an amino acid is hydrophobic or hydrophilic? (other than memorization) I know that it has something to do with the R groups of the amino acids, and that polar molecules are hydrophilic, while nonpolar molecules are…
suomynonA
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Is cysteine deficiency possible?
Is there such a thing as cysteine deficiency in humans or other mammals?
What effects would such a deficiency have?
As I understand it, most cysteine for humans comes from dietary sources, though it can be biosynthesized in humans.
Joe
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Understanding the Amino Acids
I'm having little trouble studying general relativity or quantum field theory, but remembering all the amino acids and being able to think about them is something that's completely, utterly and absolutely, defeated me...
How do I think about the…
bolbteppa
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Koshi and Goldstein substitution matrix
In their article (Context-dependent optimal substitution matrices for exposed residues (Koshi-Goldstein, 1995)), more precisely in the substitution matrix displayed in Figure 2, one one hand, the legend says:
"Graphical representation of the…
