atomicone said:
Interesting. Is there that big of a difference between the two?
My understanding is there isn't much, if any, of a difference in effects. A human user could probably never tell which one they were taking. The difference would be noticable to scientists conducting lab experiments using objective measures.
Gropep is the company which originally engineered and patented IGF-1LR3. The following is from their website. You'll notice the difference between media and receptor is in the purity, which is >85% and >95% respectively.
MaxRep
_______________________________________________________________
Human LONGRIGF-I (Media Grade)
Description:
GroPep scientists have produced Media Grade human LONGRIGF-I to provide an inexpensive yet high quality potent IGF-I analog for use as a growth factor supplement for serum-free or reduced-serum culture media. GroPep scientists have engineered this analog with the express purpose of increasing the biological activity of the IGF-I molecule. LONGRIGF-I is significantly more potent than human IGF-I in vitro. The enhanced potency is due to decreased binding of LONGRIGF-I to IGF binding proteins which normally inhibit the biological actions of IGFs.
LONG is a trade mark owned by GroPep Limited
LONGRIGF-I is covered by the following patents assigned to GroPep:
US patent 5,330,971; European patent 429,586; Japanese patent 2,682,738; Australian patent 633,099; Canadian patent 2,033,176
Purity:
> 85 % (by HPLC)
Molecular Weight:
9110 +/- 2 daltons confirmed by Mass Spectrometry
N-terminal sequence analysis:
18 residues > 95 % single sequence
Human LONGRIGF-I (Receptor Grade)
Description:
Human LONGR Insulin-like Growth Factor-I (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 for the Glu at position 3 (hence R), and a 13 amino acid extension peptide at the N-terminus. GroPep scientists have engineered this analog with the express purpose of increasing biological activity. Human LONGRIGF-I is significantly more potent than human IGF-I in vitro. The enhanced potency is due to the markedly decreased binding of human LONGRIGF-I to IGF binding proteins which normally inhibit the biological actions of IGFs.
LONG is a trade mark owned by GroPep Limited
LONGRIGF-I is covered by the following patents assigned to GroPep:
US patent 5,330,971; European patent 429,586; Japanese patent 2,682,738; Australian patent 633,099; Canadian patent 2,033,176;
Purity:
>95 % (by HPLC and N-terminal sequence analysis)
Molecular Weight:
9111 daltons confirmed by Mass Spectrometry
N-terminal sequence analysis:
18 residues > 95 % single sequence