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IGF-1 consists of 70 amino acids in a single chain with three intramolecular disulfide bridges.
The most effective form of IGF is Long R3 IGF-1, it has been chemically altered and has had amino acid changes which cause it to avoid binding to proteins in the human body and allow it to have a much longer half life, around 20-30 hours. "Long R3 IGF-1 is an 83 amino acid analog of IGF-1 comprising the complete to human.