Monday, November 3, 2008

Amino Acid activation

Codons of an mRNA molecule contain genetic messages that are carried by the mRNA and they need to be translated to form the corresponding sequence of amino acids that will form the polypeptide chain and subsequently the protein.
The tRNA transfers amino acids from the cytoplasm's pool of amino acids. Subsequently, the translation is done by tRNA. Amino acid activation occurs when each amino acid attaches itself to a tRNA. It is very specific, as each tRNA can only be linked to one particular amino acid.
Each tRNA carries an anti-codon which is the cause of the tRNA's specificity. One specific tRNA recognizes and carries only the amino acid specific by the mRNA codon. Amino acid activation si catalysed by the enzyme amino acyl tRNA synthetase. There is only one AATS for every amino acid present in the protein. ATP is required in the process and amino acyl tRNA adenylate is formed.
One amino acid and one ATP molecule will attach to the enzyme's active site. The appropriate tRNA then binds to the active site of the enzyme AATS.
A covalent bond is then formed between amino acids and the 3' end of the tRNA, and ATP is hydrolysed. An activated amino acid (amino acyl tRNA is formed and released from the active site of the enzyme).

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