Is someone able to please go into thorough detail on MT1 VS MT2?
I'm extremely interested. I've been unable to find much information on MT1 although there is bucket loads on MT2.
i am not the writer of this text, its from the old .org i copied dont know the original topic starter but here is a copy:
When assessing a potential peptide sequence for effectiveness, there are 3 issues to consider]
In studies carried out on amphibians or lizards, all natural MSH peptides (alpha, beta, and gamma) had the following order of potency at the melanocortic receptor sites.
* * * * * * * * * * * MC1 > MC3 > MC4 > MC5
Selectivity refers to how strongly the binding of the peptide is at one receptor site compared to the others. In the case of natural alpha-MSH, this peptide is very selective to the MC-1R receptor. Interestingly, while the beta-MSH and gamma-MSH are almost as selective as alpha-MSH at the MC-1R site, they are an order of magnitude less potent.
But, all natural MSH peptides lack stability and so their effects are short-lived.
Now, as I look over my stats for the syntheic melanocortic peptides, namely melanotan-1 (NDP-MSH) and melanotan II, I see the following differences.
melanotan-1 has the same binding affinity order as natural alpha-MSH]
* * * * * * * * MC1 > MC3 > MC4 > MC5
However, melanotan II has a slight twist with its ordering ...
* * * * * * * * MC1 > MC4 > MC3 > MC5
Next, melanotan-1 is the most potent peptide at the MC-1R site, followed closely by natural a-MSH and somewhat closely by melanotan II. Without describing exactly how potency is measured, I'll just present the values at the MC-1R where the lower number means more potent ...
melanotan-1 = 0.085
a-MSH = 0.12
melanotan II = 0.67
Also, interestingly melanotan-1 is the most potent peptide at each of the other receptors compared to natural a-MSH and melanotan II. However, because melanotan-1 is a relatively lengthy linear peptide, it generally cannot cross the blood-brain barrier into the brain to make its impact on the MC-4R receptor when administered centrally as well as melanotan II can. Since melanotan II is a short cyclic peptide and it can cross the bbb with ease, its effects at MC-4R are noticeable.
Neither synthetic peptide is ultra selective at any particular receptor site. However, in comparison melanotan II is most selective at the MC-1R and MC-4R sites whereas, melanotan-1 will basically bind with any receptor it comes into contact with.
Both of these peptides are more stable than compared to natural a-MSH and so their effects will last much longer.
So, in conclusion .. the answer to which peptide works best for tanning? This fight goes to melanotan-1.
Why then does melanotan-1 require more of a dose than melanotan II to achieve the same degree of tanning? For example, melanotan-1 was given at 0.16mg/kg and melanotan II was administered at 0.020mg/kg.
The answer is simple. The Amino Acid count for the linear melanotan-1 peptide is approximately twice that of the cyclic melanotan II. Also taking into consideration the difference in weight of various AAs that make up each peptide, 1mg of melanotan II packs many more individual AA chains than does 1mg of melanotan-1. Thus, the more singular peptides you have per mg, the more receptors you will bind. This means I can activate an order of magnitude more melanocytes to induce melanogenisis with melanotan II than I can given an equally weighted amount of melanotan-1.
You can think of it like this. If each item in my bag of groceries will have an almost similar effect, I would rather have the bag full of marble-sized items than the bag of lemon-sized items to experiment with. To achieve the same effect with the lemons, I'd need like 10 bags or something.
This is why many experimentors choose to use melanotan II for tanning even though melanotan-1 works better. It is more cost effective to do so.
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