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Why IGF-1 and its analogue are least soluble near neutral pH

Published 24 October 2026 · REVIVE LAB UAE Research Desk · 5 min read
The net charge of a protein is zero at its isoelectric point, and there, with no electrostatic repulsion between molecules, solubility is lowest and aggregation most likely. IGF-1 has a calculated isoelectric point near 8.5; the LR3 extension and the arginine substitution raise it a little. In the mildly acidic range the protein is positively charged and dissolves well, which is why recombinant IGF-1 preparations are typically formulated in dilute acid. Near neutral pH, at high concentration, it is prone to precipitate.

The chemistry

Acidic residues carry negative charge above about pH 4; basic residues carry positive charge below about pH 10. Between those, the net charge passes through zero at the isoelectric point. For IGF-1 the balance of lysines, arginines and histidines against aspartates and glutamates puts that point on the basic side of neutral.

Below the isoelectric point the molecules repel one another and stay in solution.

Consequences

Concentrated solutions near neutral pH can turn cloudy; the same protein in dilute acid stays clear. Buffers with high ionic strength screen the charges and reduce the effect. The lyophilised cake has no such problem until it is dissolved. These are properties of the molecule, stated here as chemistry.

Commercial culture-media supplements of LR3 are supplied in acidic solution for this reason.

What this page does not say

What to dissolve the product in or at what concentration. The supplied water vial is in the pack; the chemistry of the protein is on this page; procedure is neither.

IGF-1 LR3 is supplied by REVIVE LAB UAE for laboratory research use only, with identity and purity documented for the batch. It is not for human or veterinary use, and no dosing, administration or protocol guidance is provided.

What it costs

FormatStrengthPriceAvailability
IGF-1 LR3 Pack1 mgAED 650In stock

Delivery is AED 40 flat and free on orders over AED 700. Payment is cash on delivery anywhere in the UAE, or USDT (TRC20) in advance, which takes 5% off the order total.

Frequently asked

The chemistry?

Acidic residues carry negative charge above about pH 4; basic residues carry positive charge below about pH 10. Between those, the net charge passes through zero at the isoelectric point. For IGF-1 the balance of lysines, arginines and histidines against aspartates and glutamates puts that point on the basic side of neutral.

Does REVIVE LAB UAE provide dosing guidance?

No. REVIVE LAB UAE supplies research materials and provides no dosing, administration or protocol guidance of any kind. Every product is sold for laboratory research use only and is not for human or veterinary consumption.

How fast is delivery in the UAE?

Stock is held in Dubai. An order confirmed before 4 PM Dubai time is dispatched the same working day, reaching Dubai and Abu Dhabi the same day and the remaining emirates within 24 hours. Delivery is AED 40 flat and free over AED 700.

IGF-1 LR3 Pack — in stock, dispatched from Dubai
HPLC-verified, lot certificate on every carton, 24-hour delivery nationwide. Browse the catalogue → All peptides UAE

Related reading

→ IGF-1 LR3 Pack — 1 mg → Why some peptides resist dissolving → Size exclusion and aggregates

Supplied for laboratory research use only. Not for human or veterinary consumption. REVIVE LAB UAE provides no dosing, administration or protocol guidance.