Amino-acids are the organic acids with amino group in alpha position (alpha-acids). They are the structural units of proteins and involved in many biochemical pathways.
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Why 20 amino acids instead of 64?
This question got me thinking about amino acids and the ambiguity in the genetic code. With 4 nucleotides in RNA and 3 per codon, there are 64 codons. However, these 64 codons only code for 20 amino ...
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Why are amino acids in biology homochiral?
Why are nearly all amino acids in organisms left-handed (exception is glycine which has no isomer) when abiotic samples typical have an even mix of left- and right-handed molecules?
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What is the prehistory of amino acids in cells?
As a followup to Why 20 amino acids instead of 64? and What is the smallest number of amino acids required for life?, I am trying to understand the prehistory of amino acids in cells.
All living ...
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What happens to dextrorotatory amino acids in humans?
As indicated by this question, most of the amino acids in the human body have the L-chirality. As enzymes also have handedness, what happens to the D-amino acids that end up within the human body? Are ...
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What is the smallest number of amino acids required for life?
Is there any hypothesis on the minimum number of amino acids required for life?
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How can a three-base codon evolve from a two-base codon?
Inspired by this question among others.
It's widely suggested that the current 3-base codon system of encoding protein sequences in DNA evolved from an earlier 2-base codon system. This makes sense ...
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How to compute properties of peptides ?
I have been tasked with writing a program for computing properties of a give set of peptides. These peptides are given as 1-letter amino acid sequences and I need to compute the following :
Length ...
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Why are 3 nucleotides used as codons for amino-acid mapping in DNA?
DNA is made of 4 unique nucleotides. When coding for a protein, a sequence of 3 nucleotides is used to code for each amino acid. Why are codons 3 nucleotides in length?
A related question can be ...
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Are there any effects of elevated Cysteine levels on cognitive function?
I'm looking at this diagram of homocysteine metabolism and see two distinct pathways that the amino acid may get metabolized to: with vitamin B12 it gets converted back into methionine, while with B6 ...
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Why does Glutamine have the symbol Q?
Spent a half hour googling this and the best I could find was this:
Now for some rhymes: Arginine = R. R we having fun yet?
Asparagine = N The kNights of Ne say "Ne".
Glutamine is a cute ...
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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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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.
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Histidine aromaticity
I understand that the imidazole ring in histidine is aromatic. I also realize that it retains it's aromaticity when protonated.
I am wondering why it is not mentioned at all in basic text books such ...
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Are there examples of PTMs that add different chemical groups (and mass) to different amino acids?
I'm talking about this type of post-translational modifications. What I'm interested in is not whether some modifications can only occur on specific amino acids (that's clear), but if the nomenclature ...
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How are proteins formed?
Somewhere, I have read that we need to consume proteins to make amino acids to make new proteins. What does it suggest? How do we make proteins from proteins?
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What is the role of Homocysteine in cognitive function?
I'm looking at this link : Homocysteine and cognitive impairments and am looking for more information on specific cognitive impairments associated with elevated levels Homocysteine. That article is ...
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Why aren't D-amino acids used in proteins? [duplicate]
Possible Duplicate:
Why are amino acids in biology homochiral?
Why are only L-amino acids used in protein construction, and not D-amino acids?
