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Questions tagged [amino-acids]

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.

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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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5answers
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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 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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3answers
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Where can you find the quantities of each amino acid of a particular protein or food?

Taking a potato as an example. If I wanted to know how much µg or % of each of it's amino acids there are in 1 gram of pure potato protein, where can I find this information? Is there a freely ...
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4answers
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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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3answers
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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 ...
4
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1answer
693 views

Effect of mutation on phenotype

Is there a type of mutation that changes the phenotype of an organism, but not the protein sequence?
6
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1answer
1k views

What is the last heavy atom of an amino acid?

I'm a electrical engineer and I'm learning about bioinformatics. I was reading this paper that uses the last heavy atom to search for active sites of a protein but what would be a heavy atom? Is it ...
4
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1answer
1k views

How does beta branching stop alpha helices from forming?

I am told that beta branching interferes with alpha helix formation. Problem is that I don't see how beta branching has anything to do with alpha-helix formation. Beta-branches are on the outside of ...
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1answer
272 views

Reading an amino acid physicochemical properties diagram

I want to know if I am reading the venn diagram correctly and why there are discrepancies in the diagrams. I'm trying to determine which amino acids are considered hydrophobic and I am using this ...
6
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1answer
2k views

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 ...
4
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2answers
331 views

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 ...
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3answers
197 views

Needleman Algorithm for Optimal Alignment of two Amino Acid Sequences

I want to compute the optimal alignment of two amino acid sequences as per the following definition from a patent: "The percentage of identity between two peptidic or nucleotidic sequences is a ...
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1answer
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Why do three nucleotides code for one amino acid? Why not 5 nucleotides? [duplicate]

We all know why there are 3-base codons, and why there aren't any 2-base codons. But why is there not a 4-base a 5-base codon?
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1answer
860 views

ATP Hydrolysis to AMP in the Urea Cycle. What is the Free Energy Change?

How is the hydrolysis of ATP into AMP and PPi in making arginosuccinate equivalent to the hydrolysis of 2 ATP?