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Banned
There is an ongoing debate on the difference in quality b/w RG and MG IGF (GFL). I'd like to put it to bed once and for all, as it's a question I get asked regularly.
To put it simply, the use and expense of RG IGF is wasted on most research, especially the kind that is likely to be done by members here. RG is for very specific methodologies of research requiring EXACTING tolerances to reduce variables in the experimentation process - specifically, mostly in the area of immunohistochemistry. (We're talking on the microscopic level within serum-free or reduced-serum culture media).
MG IGF is a lesser expensive form of the exact same product with the same purity standard. MG is also for precise experimentation but designed as a more affordable alternative for use in experiments not demanding the exacting tolerances necessitating RG. (1)
Here is the info directly from the manufacturer's (and patent holder's) website:
Human LONG™R³IGF-I (Media Grade)
Purity: > 85 % (by N-terminal sequence analysis)
Molecular Weight: 9110 +/- 2 daltons – confirmed by Mass Spectrometry
N-terminal sequence analysis: 18 residues > 95 % single sequence
Biological Activity: Type 1 IGF receptor binding assay: ED50 > 15 ng/ml
IGF binding protein assay: ED50 > 200 ng/ml
Stimulation of protein synthesis in rat L6 myoblasts: ED50 < 10 ng/ml
Endotoxin: < 0.1 EU/µg
Human LONG™R³IGF-I (Receptor Grade)
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
Biological Activity: Type 1 IGF receptor binding assay: ED50 > 15 ng/ml
IGF binding protein assay: ED50 >200 ng/ml
Stimulation of protein synthesis in rat L6 myoblasts: ED50 < 10 ng/ml
Endotoxin: < 0.1 EU/µg
So above you can see the purity is slightly different (3), and the only other marked difference (if you can even consider it “marked”) is the molecular weight. The media grade may be off a dalton or two from the receptor grade.
Allow me to put this into a little plainer form of English. You can drive a Ferrari or a High Performance BMW M series. Both are hand-built. Both go real fast. You will get plenty of ass driving either one. But you can’t open up either one on the freeway because you’re hampered by traffic, speed limits, etc…
What’s the diff. then? You’ll pay about a hundred grand for the BMW, and about five times that for the Ferrari. Why!?!
I’ve seen many posts on IGF and many of them say many different things. Many of them say the same thing. Doesn’t mean any of them are right.
I saw a post by someone who is a rather respected Vet on the boards who stated “Only buy Lyophilized powder form of IGF! This is the only way it comes and any other form is faked, or junk, or ruined”. (2) Not true. Yes, Lyophilized powder is more stable than an improperly reconstituted form, but there are other factors that will play into that purchase. Perhaps the most import reason you don’t want to buy Lyo IGF is the fact that the IGF peptide is EXTREMELY delicate. It’s best to operate in a nitrogen environment, and when possible (and necessary) at slight vacuum (-25 kPa to be more specific).
Filtering requires some special skill and equipment also. (Taken from manufacturer’s site: Filter Sterilization of GroPep Peptides If sterilization is required, the peptide solution should be filter sterilized using a membrane with low protein binding; an example of this is the Millipore Millex-GV Cat. No. SLGV025LS.
Note that extreme care must be exercised in filtering dilute protein solutions because of the likelihood of adsorption to the filter. Growth factors require the same care in handling. Filtration for sterility is best done on either the 1 mg/ml stock solution or the 0.1 mg/ml working solution diluted in 10 mM HCl. It may be possible to filter more dilute solutions if a carrier protein is present but caution should be exercised.
Important Recommendations:
*Do not add the peptide to low protein or protein free media prior to filter sterilization.
*Use a filter membrane with low protein binding characteristics.
*Filter sterilize the IGF peptide separately at a concentration of 0.1 mg/ml (diluted in 10mM HCl) or greater.)
Chances that you’re going to fuck it up… ? Pretty damn good. This is why you want to buy your IGF properly reconstituted and in the proper medium with the right pH (done with HCL acid (10 mM HCl), not vinegar or many of the other “methods” I’ve seen lately).
I’ve also seen many posts from equally respected Vets touting the advantages of RG over MG and why the only IGF with which to go is RG. They are equally mistaken and equally unqualified to render this opinion as the person referred to above. It’s not true. Plain and simple.
After all this… will I get you RG? Sure. I’d love to. It definitely helps my bottom line on the sales reports. But I can’t help but feel like I’m ripping people off when I do. Do yourselves a favor, for the cost of one unit of RG, buy 4 or 5 MG and you can go hog wild with it. Nonetheless, I still have a couple clients that insist upon buying the RG.
(1) From the manufacturer's website: GroPep scientists have produced Media Grade human LONG™R³IGF-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. LONG™R³IGF-I is significantly more potent than human IGF-I in vitro. The enhanced potency is due to decreased binding of LONG™R³IGF-I to IGF binding proteins which normally inhibit the biological actions of IGFs.
(2) Just as a point of clarification: I see posts here and there about how IGF did nothing for someone or they think they were sammed. Chances are, a large percentage of these posts are a result of damaged IGF and not necessarily a scam. Although a small amount of these people may have been scammed, IGF is extremely delicate. Improper reconstitution, storage, shipping methods, excessive vibration, buying it 2nd, 3rd, 4th -hand, etc... can all cause the IGF peptide to erode. This is why it is critical that you know the source of the IGF and how it was reconstituted, etc.
(3) I contacted Gropep and the explaination they gave goes like this: The purity of the MG is actually supposed to read >85% [so editted above]; however, most of the media grade actually far surpasses that standard and is not much different that RG, only that they cannot guarantee the purity standard exceeds that of the RG, and thus, sell it as MG. The letter from Gropep also was sure to state at the very end "Be aware that NO GroPep product is approved for use in humans."
To put it simply, the use and expense of RG IGF is wasted on most research, especially the kind that is likely to be done by members here. RG is for very specific methodologies of research requiring EXACTING tolerances to reduce variables in the experimentation process - specifically, mostly in the area of immunohistochemistry. (We're talking on the microscopic level within serum-free or reduced-serum culture media).
MG IGF is a lesser expensive form of the exact same product with the same purity standard. MG is also for precise experimentation but designed as a more affordable alternative for use in experiments not demanding the exacting tolerances necessitating RG. (1)
Here is the info directly from the manufacturer's (and patent holder's) website:
Human LONG™R³IGF-I (Media Grade)
Purity: > 85 % (by N-terminal sequence analysis)
Molecular Weight: 9110 +/- 2 daltons – confirmed by Mass Spectrometry
N-terminal sequence analysis: 18 residues > 95 % single sequence
Biological Activity: Type 1 IGF receptor binding assay: ED50 > 15 ng/ml
IGF binding protein assay: ED50 > 200 ng/ml
Stimulation of protein synthesis in rat L6 myoblasts: ED50 < 10 ng/ml
Endotoxin: < 0.1 EU/µg
Human LONG™R³IGF-I (Receptor Grade)
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
Biological Activity: Type 1 IGF receptor binding assay: ED50 > 15 ng/ml
IGF binding protein assay: ED50 >200 ng/ml
Stimulation of protein synthesis in rat L6 myoblasts: ED50 < 10 ng/ml
Endotoxin: < 0.1 EU/µg
So above you can see the purity is slightly different (3), and the only other marked difference (if you can even consider it “marked”) is the molecular weight. The media grade may be off a dalton or two from the receptor grade.
Allow me to put this into a little plainer form of English. You can drive a Ferrari or a High Performance BMW M series. Both are hand-built. Both go real fast. You will get plenty of ass driving either one. But you can’t open up either one on the freeway because you’re hampered by traffic, speed limits, etc…
What’s the diff. then? You’ll pay about a hundred grand for the BMW, and about five times that for the Ferrari. Why!?!
I’ve seen many posts on IGF and many of them say many different things. Many of them say the same thing. Doesn’t mean any of them are right.
I saw a post by someone who is a rather respected Vet on the boards who stated “Only buy Lyophilized powder form of IGF! This is the only way it comes and any other form is faked, or junk, or ruined”. (2) Not true. Yes, Lyophilized powder is more stable than an improperly reconstituted form, but there are other factors that will play into that purchase. Perhaps the most import reason you don’t want to buy Lyo IGF is the fact that the IGF peptide is EXTREMELY delicate. It’s best to operate in a nitrogen environment, and when possible (and necessary) at slight vacuum (-25 kPa to be more specific).
Filtering requires some special skill and equipment also. (Taken from manufacturer’s site: Filter Sterilization of GroPep Peptides If sterilization is required, the peptide solution should be filter sterilized using a membrane with low protein binding; an example of this is the Millipore Millex-GV Cat. No. SLGV025LS.
Note that extreme care must be exercised in filtering dilute protein solutions because of the likelihood of adsorption to the filter. Growth factors require the same care in handling. Filtration for sterility is best done on either the 1 mg/ml stock solution or the 0.1 mg/ml working solution diluted in 10 mM HCl. It may be possible to filter more dilute solutions if a carrier protein is present but caution should be exercised.
Important Recommendations:
*Do not add the peptide to low protein or protein free media prior to filter sterilization.
*Use a filter membrane with low protein binding characteristics.
*Filter sterilize the IGF peptide separately at a concentration of 0.1 mg/ml (diluted in 10mM HCl) or greater.)
Chances that you’re going to fuck it up… ? Pretty damn good. This is why you want to buy your IGF properly reconstituted and in the proper medium with the right pH (done with HCL acid (10 mM HCl), not vinegar or many of the other “methods” I’ve seen lately).
I’ve also seen many posts from equally respected Vets touting the advantages of RG over MG and why the only IGF with which to go is RG. They are equally mistaken and equally unqualified to render this opinion as the person referred to above. It’s not true. Plain and simple.
After all this… will I get you RG? Sure. I’d love to. It definitely helps my bottom line on the sales reports. But I can’t help but feel like I’m ripping people off when I do. Do yourselves a favor, for the cost of one unit of RG, buy 4 or 5 MG and you can go hog wild with it. Nonetheless, I still have a couple clients that insist upon buying the RG.
(1) From the manufacturer's website: GroPep scientists have produced Media Grade human LONG™R³IGF-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. LONG™R³IGF-I is significantly more potent than human IGF-I in vitro. The enhanced potency is due to decreased binding of LONG™R³IGF-I to IGF binding proteins which normally inhibit the biological actions of IGFs.
(2) Just as a point of clarification: I see posts here and there about how IGF did nothing for someone or they think they were sammed. Chances are, a large percentage of these posts are a result of damaged IGF and not necessarily a scam. Although a small amount of these people may have been scammed, IGF is extremely delicate. Improper reconstitution, storage, shipping methods, excessive vibration, buying it 2nd, 3rd, 4th -hand, etc... can all cause the IGF peptide to erode. This is why it is critical that you know the source of the IGF and how it was reconstituted, etc.
(3) I contacted Gropep and the explaination they gave goes like this: The purity of the MG is actually supposed to read >85% [so editted above]; however, most of the media grade actually far surpasses that standard and is not much different that RG, only that they cannot guarantee the purity standard exceeds that of the RG, and thus, sell it as MG. The letter from Gropep also was sure to state at the very end "Be aware that NO GroPep product is approved for use in humans."
