# Preventing Protein Damage with Extra Methionine

> This 1993 patent describes how adding extra methionine to protein-based medicines can prevent them from degrading, especially in liquid or semi-solid forms.

- **Patent:** US 5272135
- **Original title:** Method for the stabilization of methionine-containing polypeptides
- **Owner:** Chiron Ophthalmics Inc
- **Granted:** 1993
- **Status:** Public domain (expired)
- **Times cited:** 63
- **Field:** pharmaceutical, biotech, materials

## What it does

This patent details a method to stop proteins, specifically those with a methionine amino acid, from oxidizing and breaking down when stored in liquid or semi-solid medicines. The key is to add extra methionine, an amino acid that is part of the protein, to the preparation. This added methionine acts as a shield, getting oxidized itself instead of the methionine within the therapeutic protein. The patent specifies adding methionine in amounts between 0.01% and 0.3% by weight or volume, ensuring that the therapeutic protein remains stable for storage and use. For example, claim 8 describes using this method with epidermal growth factor in a liquid solution.

## What it does NOT cover

- Methods that do not involve adding methionine to inhibit oxidation.
- Methods for stabilizing proteins that do not contain any methionine residues.
- Stabilization of proteins in solid dosage forms (e.g., pills, powders).
- Adding methionine in concentrations outside the specified range of 0.01% to 0.3%.
- Inhibiting oxidation of molecules other than polypeptides.

## The clever bit

The inventors realized that methionine, an amino acid naturally present in many proteins, is particularly susceptible to oxidation. By adding extra methionine to the formulation, they created a sacrificial agent that preferentially oxidizes, thereby protecting the methionine residues within the therapeutic protein itself.

## Real-world examples

1. Ophthalmic solutions containing growth factors
2. Creams or ointments with therapeutic proteins
3. Liquid formulations of recombinant proteins

## Why it matters

This patent addresses a critical challenge in biopharmaceutical development: maintaining the stability and efficacy of protein-based drugs. Proteins are delicate molecules prone to degradation, which can render them useless or even harmful. By providing a simple yet effective method to prevent oxidation, this patent likely contributed to the viability of developing and commercializing various protein therapeutics, particularly those intended for topical or injectable use.

## Frequently asked questions

### What does Preventing Protein Damage with Extra Methionine cover?

This 1993 patent describes how adding extra methionine to protein-based medicines can prevent them from degrading, especially in liquid or semi-solid forms.

### Who owns patent US 5272135?

Chiron Ophthalmics Inc owns this patent, granted in 1993.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 5272135 cited by?

This patent has been cited by 63 later patents that build on its ideas.

### What problem does this patent solve?

This patent addresses a critical challenge in biopharmaceutical development: maintaining the stability and efficacy of protein-based drugs. Proteins are delicate molecules prone to degradation, which can render them useless or even harmful. By providing a simple yet effective method to prevent oxidation, this patent likely contributed to the viability of developing and commercializing various protein therapeutics, particularly those intended for topical or injectable use.

### What does this patent NOT cover?

Methods that do not involve adding methionine to inhibit oxidation.

**Full plain-English explainer:** https://patentbrief.org/patent/us/5272135/lipitor-atorvastatin

**Original patent:** https://patents.google.com/patent/US5272135

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._