So Peg MGF is better than MGF ??? Is that correct ??? Because of the longer half life of PEG MGF ???
PEG is often used as shorthand for PEGylation (the process of attaching PEG to a compound)
PEG really though is
poly
ethylene
glycol.
In order to protect a drug or compound from either enzyme degradation or from the body seeing the drug/compound as something it needs to destroy certain things can be done.
One of those things is attaching PEG to the drug or compound.
MGF (is a variant of IGF-1). If you inject it into plasma it will degrade pretty quickly. You can still buy MGF but it just breaks down too quickly.
If you take PEG and attach it to the structure of MGF you "shelter" certain portions of the structure that are easily degradable.
For instance the amino acid Arginine & Lysine are subject to degradation unless protected from enzymes that want to break it apart. PEG either blocks them from getting to those weak points or from recognizing them in the first place.
So PEG-MGF has a longer life when injected into plasma.
Now you can attach PEG in several places on a peptide. I believe there are two versions of PEG-MGF which vary by where PEG is attached. One anecdotally is working better then the other.
Why?
Because when you attach PEG to a peptide to shelter it you might also change its ability to bind to a receptor. The ability or strength of binding is often called "affinity".
So one of the PEG-MGFs probably has a stronger binding affinity for the IGF-1 receptor then the other.
In fact that one PEG-MGF probably has a stronger binding affinity for the IGF-1 receptor then IGF-1 LR3. Which makes PEG-MGF a better IGF-1 then IGF-1 LR3.
So we have two things to consider... longevity of the peptide and binding affinity.
Regular MGF has no alteration and may have a stronger binding to the IGF-1 receptor then PEG-MGF BUT its short life and susceptibility to quick breakdown mean far less of it will actually end up bound to an IGF-1 receptor.
PEG-MGF has a longer life and although it may not bind as strongly or quickly eventually more of it will bind to an IGF-1 receptor.