IGF-1 LR3 FAQ: Storage, Mixing and Stability

The questions below are the ones researchers ask most about storing, mixing and handling IGF-1 LR3. Each answer reflects what it is: an 83-residue recombinant analogue of human IGF-I, folded by three disulfide bridges, supplied as a 1 mg lyophilised vial. Each links to the fuller page where there is one.

How long does IGF-1 LR3 last in the fridge after mixing?

Vistara Labs’ general handling window is 8 to 12 weeks at 2 to 8 °C in the dark, with quality fading from around week 6 to 8. Supplier figures for the protein in plain water are shorter: one week at 4 °C on one sheet, and one month undiluted on another. A mixed vial is best made close to use and used early in the window. The full table is on how long IGF-1 LR3 lasts.

How long does unmixed IGF-1 LR3 powder last?

One supplier rates the lyophilised protein at 2 years at minus 20 °C; another rates it at 6 months at 2 to 8 °C or long term at minus 20 °C, with a shelf life of one year from despatch. Days at room temperature in transit do not harm the sealed powder, so it ships without an ice pack.

Why is IGF-1 LR3 more delicate than small peptides?

At 83 residues it is a small folded protein, held in shape by three disulfide bridges. Besides the chemical changes any peptide can undergo, it can lose its fold at air bubbles, rearrange its disulfide bonds and stick to surfaces when dilute. Those physical changes barely apply to a short peptide, which is why its supplier solution figures are shorter.

What is the weak point of IGF-1 LR3 in solution?

Several, rather than one. Its methionines oxidise faster with light, oxygen and warmth, as formulation studies on human IGF-I showed (Fransson et al., Pharmaceutical Research, 1996). Light and trace iron also drive covalent dimers through disulfide scrambling. Shaking unfolds and aggregates it. The details are on the IGF-1 LR3 stability page.

What do you mix IGF-1 LR3 with?

Bacteriostatic water, which is sterile water with 0.9% benzyl alcohol so a refrigerated vial can be accessed more than once. Both supplier sheets reconstitute the protein in water, one at 0.1 to 1.0 mg/mL, and it needs no acid. Phosphate buffer is avoided for a stored solution because it increased methionine oxidation in human IGF-I. The reasons are on the IGF-1 LR3 solubility guide.

How much bacteriostatic water goes in a 1 mg IGF-1 LR3 vial?

There is no single correct volume. With 2 mL a 1 mg vial gives 0.5 mg/mL; with 1 mL it gives 1 mg/mL. Every volume from 1 to 5 mL keeps the solution inside the supplier range of 0.1 to 1.0 mg/mL. Write the chosen concentration on the vial. The tables and calculator are on the IGF-1 LR3 reconstitution page.

Why should IGF-1 LR3 not be shaken?

Shaking creates air and liquid interfaces, and folded proteins unfold and clump there. A short peptide is far less affected. Add the water down the wall of the vial, swirl gently, and if the cake is slow to dissolve, let the vial stand for a few minutes and swirl again.

Why is my IGF-1 LR3 cloudy after mixing?

Brief cloudiness that clears within 10 to 15 minutes is usually trapped air from adding water too fast. Haze that persists usually means the protein was shaken or vortexed and has started to aggregate. Haze, particles or a tint that appear later point to warm storage, light, freezing or contamination, and the solution is discarded. More in why peptides gel or go cloudy.

Can you freeze mixed IGF-1 LR3?

Not a vial that will be opened again. Both supplier sheets recommend freezing solution as single-use aliquots for longer storage, one of them with a carrier protein added, and one warns against repeated freezing and thawing. Thaw each aliquot once. Sealed powder can be frozen at minus 20 °C without concern.

Does IGF-1 LR3 need to be kept out of the light?

Yes. In formulation studies on human IGF-I, visible light increased methionine oxidation and drove covalent dimers. Keep the vial boxed in the main body of the fridge and return it after each access.