To Freeze or Not To Freeze: Lyophilized Peptides

Peptides should be stored in solution only for short periods of time. For long-term storage the peptide should be lyophilized from a volatile buffer or solvent and stored desiccated at -20 °C.

Grant, Gregory A. (2002). Synthetic Peptides: A Users's Guide. p 283.


The best storage and handling conditions will depend on peptide sequence. However, despite the individuality of peptide sequences, some general recommendations for peptide handling can be made (Table 7).
Table 7:
Duration of storage

Concentrated stock solution (0.5–2 nmol/μL): storage duration depends on peptide

Short-term (≤3 months): high concentration (1–100 pmol/μL) liquid solution at 4 °C or frozen solution at −20 °C to −80 °C

Medium-term (3 months to 1 year; peptide-dependent): frozen solution at high concentration

Long-term (>1 year): lyophilized at −20 °C to −80 °C
 
Grant, Gregory A. (2002). Synthetic Peptides: A Users's Guide. p 283.



Table 7:


Tl;dr: so you're on the pro-freezer side of the debate?

I'm fridge but really fridge/freezer seems minutiae compared to either vs. room temperature.
 
Tl;dr: so you're on the pro-freezer side of the debate?

I store mine in the freezer, but my main point is that the people who are saying the freezer is bad are wrong and using bro science to justify it. There is nothing to debate. The science on this has been known for decades. In general if you want to store lyophilized peptides for > 3 months, the freezer is the best place.

I'm fridge but really fridge/freezer seems minutiae compared to either vs. room temperature.

Like the above study says, it depends on the peptide. If you go read the study that ghoul grabbed graphs from but didn't link the source, it shows that the bilirubin actually degraded quite a bit in the refrigerator (4%) but not in the freezer.
 
There is nothing to debate. The science on this has been known for decades. In general if you want to store lyophilized peptides for > 3 months, the freezer is the best place.

We're talking about only lyophilized peptides (not reconstituted). And yeah, fridge or freezer. Not room temperature.
 
Like the above study says, it depends on the peptide. If you go read the study that ghoul grabbed graphs from but didn't link the source, it shows that the bilirubin actually degraded quite a bit in the refrigerator (4%) but not in the freezer.

Bilirubin is not a good example. Not a peptide.

Was it reconstituted? If so, kinda interesting (light exposure conditions?), but doesn't provide insight into the questions being asked here.
 
BTW, I was lazy in referencing the example. It was bivalirudin that degraded 4% at 4C. Bivalirudin Is a peptide.

My guess is it’ll be different for each individual peptide. Phizer says explicitly not to freeze Lyophilized HGH powder and to store it under refrigeration.

GENOTROPIN® (somatropin) How Supplied/Storage and Handling | Pfizer Medical Information - US

Edit: Omnitrope also says to refrigerate before and after reconstitution.

 
My guess is it’ll be different for each individual peptide.

For sure. The study I referenced earlier explicitly says it depends on the peptide, but then says the general advice is to store at -20C.

Phizer says explicitly not to freeze Lyophilized HGH powder and to store it under refrigeration.

HGH is s tough one. Definitely, as you've pointed out, some say refrigerate rather than freeze. There a bunch of other manufacturers, though, who say store their's at -20C. Fortunately, I'm in a test of UGL HGH that has been stored for 6 months in the freezer. We already have a before test of the batch so the after test should give us some insight on whether this UGL HGH is best stored in the freezer.
 
For sure. The study I referenced earlier explicitly says it depends on the peptide, but then says the general advice is to store at -20C.



HGH is s tough one. Definitely, as you've pointed out, some say refrigerate rather than freeze. There a bunch of other manufacturers, though, who say store their's at -20C. Fortunately, I'm in a test of UGL HGH that has been stored for 6 months in the freezer. We already have a before test of the batch so the after test should give us some insight on whether this UGL HGH is best stored in the freezer.

Hope you come back here and report the findings! I’d be very interested.
 
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