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.
Original patent title: “Method for the stabilization of methionine-containing polypeptides”
This 1993 patent describes how adding extra methionine to protein-based medicines can prevent them from degrading, especially in liquid or semi-solid forms. Granted to Chiron Ophthalmics Inc in 1993 with 28 claims and 63 forward citations.
Key facts
Coverage
What does this patent actually cover?
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, claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 8 describes using this method with epidermal growth factor in a liquid solution.
The gap
What does this patent 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
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.
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Ophthalmic solutions containing growth factors
Creams or ointments with therapeutic proteins
Liquid formulations of recombinant proteins
Why it matters
The bigger picture
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.
Filed
March 1, 1991
Granted
December 21, 1993
Market context
Who's building on this
Companies in this space
Companies developing protein-based therapeutics, particularly those in ophthalmology, dermatology, and regenerative medicine, would have considered this patent. Many large pharmaceutical companies with biopharmaceutical divisions and smaller biotech startups focused on novel protein drugs would be impacted.
Market impact
This patent likely enabled the development and commercialization of stable, liquid or semi-solid protein-based pharmaceuticals that might otherwise have degraded too quickly. It provided a clear technical solution for a common problem in biopharmaceutical formulation, potentially influencing how such drugs are designed and manufactured.
Claim 1 — Plain English
What this patent covers
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.
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.
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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
PatentBrief Score
Impact Score
Moderate
Citation count
36/40
Highly cited
Claim breadth
19/20
Very broad protection
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$88K – $281K
Midpoint $176K · expired or expiring · industry ×3.0
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
28 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Takruri, H. (1993). Preventing Protein Damage with Extra Methionine (U.S. Patent No. 5,272,135). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/5272135/lipitor-atorvastatin
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
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.
Patent monitoring