The Product: Long[R3] insulin-like growth factor-I (Long[R3]IGF-I) is an 83 amino acid analog of human IGF-I comprising the complete human IGF-I sequence with the substitution of an Arg (R) for the Glu (E) at position 3 (hence R3), and a 13 amino acid extension peptide at the N-terminus. GroPeo sientists have engineered this analog with the express purpose of increasing iological activity. Long[R3]IGF-I is significantly more potent than IGF-I in vitro and in vivo. The enhanced potency is due to the markedly decreased binding of long R3 IGF-I to all IGF binding proteins. These binding proteins normally inhibit the biological actions of IGFs.Source: Long[R3]IGF-I is produced in E. coli using a patented expression system the Long[R3]IGF-I is correctly folded and purified by several chromatography steps to yield Receptor Grade Long[R3]IGF-I.Purity: >85% (as determined by HPLC and N-terminal sequence analysis)Molecular Weight: 9111.6 daltons - confirmed by Mass SpectrometryN-terminal sequence analysis of recombinant product: 18 residues >95% single sequenceBiological Activity: (stimulation of protein synthesis in rat L6 myoblasts) ED50 <10 ng/mlEndotoxin (LAL): <0.1 EU/ug