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 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?
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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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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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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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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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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 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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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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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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Why 22 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 22 ...
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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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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?