US Patent 5,695,968: What the claims actually cover, where they sit in the competitive landscape, and what is most likely to matter for enforceability
What does US 5,695,968 claim, in operational terms?
US 5,695,968 claims a process that converts D-N-carbamoyl-α-amino acids (general structure: R-CH(NHCO NH2)-COOH) into the corresponding D-α-amino acids (carbamoyl removed) in aqueous medium using an enzyme that is produced by a genetically engineered bacterial transformant. The transformation is implemented via a recombinant DNA system that encodes a D-N-carbamoyl-α-amino acid amidohydrolase (carbamoyl-removing hydrolase).
The three independent claims you provided are variations on the same core method:
- Claim 1: Uses an enzyme made in a transformant derived from host E. coli JM 109 with one of four specific plasmids: pAHD 101, pAD 108, pPHD 301, pPD 304.
- Claim 2: Same conversion concept, but ties the transformant explicitly to E. coli JM 109 strains carrying those plasmids (including FERM BP numbers).
- Claim 3: Same conversion, but specifies the enzyme is produced by a bacterium from Pseudomonas sp. (two strains: KNK 0030A and KNK 505, with FERM BP numbers).
Claim scope in one line
The claims are limited to (1) a substrate class (D-N-carbamoyl-α-amino acids with a constrained R), (2) aqueous conversion, and (3) carbamoyl removal via a specific enzyme source, defined by either specific plasmids in E. coli JM 109 (Claims 1 and 2) or specific Pseudomonas strains (Claim 3).
How broad is the substrate definition (R-group), and where are the built-in limits?
All three claims use essentially the same substrate template:
R-CH(NHCONH2)-COOH, where R can be:
- Phenyl
- Phenyl substituted with hydroxy (hydroxyl at o-, m-, or p-positions; “optionally” one or more hydroxyl groups in Claim 1; Claim 2 and 3 make the hydroxyl substitution explicit as one or more hydroxyl groups)
- Alkyl C1 to C4
- Alkyl C1 to C4 substituted with hydroxy, alkylthio, carboxyl, amino, phenyl, phenyl substituted with hydroxy, or amido
- Aralkyl C7 to C8
- Thienyl
Practical breadth assessment
- The R definition is chemically diverse (aromatic, heteroaromatic, and several aliphatic and functionalized variants).
- The claim does not read on other carbamoyl-activated amino acid variants where the leaving group or backbone differs from the defined D-N-carbamoyl-α-amino acid.
- The claim is also structural-logic constrained: it requires the substrate to be the carbamoylated D-α-amino acid and the product to be the corresponding D-α-amino acid, consistent with an amidohydrolase de-carbamoylation mechanism.
What is the claimed biocatalytic step, and how much does “aqueous medium” matter?
Each claim requires:
- Conversion occurs in aqueous medium.
- Enzyme removes carbamoyl groups from D-N-carbamoyl-α-amino acids to give D-α-amino acids.
- After conversion, D-α-amino acids are collected (no specific downstream purification method is claimed).
Why “aqueous medium” is not likely the main battleground
Most industrial enzymatic steps for amino acid transformation occur in water-based systems. The more enforceable distinctions in this claim set are:
- enzyme identity by genetic origin (plasmid-defined recombinant transformant or specific Pseudomonas strains),
- and the substrate class.
“Aqueous medium” is therefore likely a low-discrimination element unless an accused process uses a substantially non-aqueous or biphasic system that still plausibly counts as “aqueous” (rare in this type of transformation).
What makes the claims potentially narrow: enzyme source is defined by plasmids or specific FERM deposit strains
The key limiting element is the origin and identity of the enzyme system:
Claim 1
Enzyme is produced by a transformant made by transforming a host bacterial cell with:
- a vector, plus
- a DNA fragment encoding the amidohydrolase, where the recombinant plasmid is limited to:
- pAHD 101
- pAD 108
- pPHD 301
- pPD 304
Claim 2
Same recombinant DNA limitation, but transformant is explicitly:
- Escherichia coli JM 109 pAHD 101
- Escherichia coli JM 109 pAD 108 (FERM BP-3184)
- Escherichia coli JM 109 pPHD 301
- Escherichia coli JM 109 pPD 304 (FERM BP-3183)
Claim 3
Enzyme is produced by a bacterium:
- Pseudomonas sp. KNK 0030A (FERM BP-3181)
- Pseudomonas sp. KNK 505 (FERM BP-3182)
Enforceability implication
For method claims of this type, a competitor can potentially avoid infringement by doing one of the following:
- Use a different amidohydrolase (different gene/enzyme) that performs the same reaction.
- Use the same or a similar enzyme, but express it in a different host with different recombinant DNA than the specified plasmids (Claims 1 and 2).
- Use a non-identical bacterial source for the enzyme (Claim 3).
The claim language does not read as “any enzyme having amidohydrolase activity.” It reads as “enzyme produced by” transformants defined by named plasmids (in E. coli JM 109) or named Pseudomonas strains (FERM deposits). That is a material narrowing factor.
Do the three claims materially overlap, or are they separate competitive “routes”?
They overlap on the chemistry and mechanism (carbamoyl removal in water). The competitive difference is the implementation route:
- Route A (Claims 1 and 2): recombinant E. coli JM 109 carrying one of four specific plasmids.
- Route B (Claim 3): production from two Pseudomonas strains.
This means an accused infringer can choose which process to adopt based on what is easiest to implement and hardest to infringe. From a landscape standpoint, the competitive question becomes: are others using these exact plasmids/FERM strains or using alternate genetic constructs?
Where are the likely “design-arounds” in the claim language?
Given the exactness of plasmid and FERM-strain references, the most straightforward design-arounds are:
-
Switch plasmids / recombinant DNA
- For processes aimed at Claim 1/2, use expression constructs other than pAHD 101, pAD 108, pPHD 301, pPD 304.
- Even if the underlying amidohydrolase is the same, the claim ties infringement to those particular plasmids in the claimed method.
-
Switch host organism
- Claims 1 and 2 explicitly reference transformants tied to E. coli JM 109.
- A different host (with the same or different vector) is a potential non-infringement lever, depending on whether “host bacterial cell” language in Claim 1 is constrained by the same E. coli limitation in the claim text you provided.
-
Use different Pseudomonas strains or non-Pseudomonas enzyme production
- Claim 3 requires enzyme produced by one of two identified Pseudomonas strains with specified FERM deposits.
-
Use a different carbamoyl-removal enzyme
- If another amidohydrolase family member (different gene/enzyme source) removes the same carbamoyl group from the same substrate class, it may fall outside the “produced by transformant” limitations.
What does the patent landscape risk look like in practice?
A complete competitive analysis normally maps:
- prior art enzymatic de-carbamoylation processes for D-α-amino acids,
- known carbamoyl removing enzymes and their genes,
- and whether later patents broaden the claimed scope beyond the specific plasmids/strains.
However, with only the claim text provided and no additional bibliographic or prosecution data, a landscape map cannot be populated with specific competitor patents or cited priority documents without risking inaccuracy.
What can be assessed from the claim wording itself is the legal risk profile:
- High risk for processes that use the same plasmids or the same FERM-deposited strains.
- Lower risk for processes that use an alternate recombinant construct or alternate amidohydrolase source, even if the reaction chemistry is the same.
Claim-by-claim breakdown: what you can prove in an infringement analysis
Claim 1: recombinant DNA in a transformant with named plasmids
A claimant would need to show all elements:
- Substrate is D-N-carbamoyl-α-amino acid where R fits the enumerated groups.
- Reaction converts to corresponding D-α-amino acid.
- Conducted in aqueous medium.
- The enzyme used is produced by a transformant made by:
- transforming a host bacterial cell with a recombinant DNA comprising a vector and a DNA fragment encoding the amidohydrolase gene,
- where the recombinant DNA/plasmid is one of: pAHD 101, pAD 108, pPHD 301, pPD 304.
Claim 2: transformant identity narrowed with FERM-linked E. coli strains
Same as Claim 1, but additional showings:
- The transformant must be one of the named E. coli JM 109 constructs, with two explicitly linked to:
- pAD 108 (FERM BP-3184)
- pPD 304 (FERM BP-3183)
Claim 3: Pseudomonas strain enzyme source
A different proof path:
- Enzyme is produced by Pseudomonas sp. strains:
- KNK 0030A (FERM BP-3181)
- KNK 505 (FERM BP-3182)
- The same substrate/product conversion and aqueous conversion steps.
Where disputes are likely to concentrate
Based on claim construction mechanics, the highest-friction factual disputes in infringement and validity contests typically cluster around:
-
Identity of the enzyme source
- Are the accused plasmids the same as pAHD 101 / pAD 108 / pPHD 301 / pPD 304?
- Are the accused bacterial production strains the same as KNK 0030A / KNK 505?
- What if the gene is similar but not the same sequence?
-
Substrate matching
- Whether the accused process uses D-N-carbamoyl-α-amino acids where R fits the exact enumerated list.
- Whether any R substitutions outside the list are present.
-
Functional equivalence vs literal requirements
- These claims are not written as “any D-N-carbamoyl-α-amino acid amidohydrolase.”
- They tie to how the enzyme is produced (transformant/plasmid or deposit strains). That reduces “equivalence” space for an accused process that uses a different gene/enzyme source.
Key Takeaways
- US 5,695,968 claims a de-carbamoylation method: converting D-N-carbamoyl-α-amino acids to D-α-amino acids in aqueous medium using a D-N-carbamoyl-α-amino acid amidohydrolase.
- The most constraining claim element is enzyme source, defined by specific plasmids in E. coli JM 109 (Claims 1 and 2) or specific Pseudomonas FERM-deposited strains (Claim 3).
- The substrate definition is moderately broad across R-group chemotypes (phenyl, hydroxy-phenyl, C1 to C4 alkyl and functionalized variants, aralkyl C7 to C8, thienyl).
- For competitive positioning, the landscape risk is highest for processes using those exact plasmids or those exact strains; it is lower for processes using different recombinant constructs or different amidohydrolase sources, even if the chemistry is the same.
FAQs
1. Does the patent claim the chemical composition of D-α-amino acids?
No. It claims a process that converts D-N-carbamoyl-α-amino acids to the corresponding D-α-amino acids via an enzyme sourced from specific recombinant constructs or strains.
2. Is the enzyme defined by activity or by genetic origin?
Both, but the claim language is materially tied to genetic origin: enzyme is “produced by” a transformant with named plasmids (Claims 1-2) or by specific deposited Pseudomonas strains (Claim 3).
3. Can a competitor avoid infringement by changing the host organism?
Potentially, because Claims 1 and 2 tie the transformant to E. coli JM 109 and named plasmids, while Claim 3 ties to Pseudomonas strains. Changing host and construct can move the process outside the claim’s defined enzyme-production route.
4. Are all hydroxy-substituted phenyls covered?
The claims cover phenyl substituted with hydroxy where the hydroxyl position is at o-, m-, or p-positions; Claim 1 uses “optionally one or more hydroxyl groups,” while Claims 2 and 3 describe one or more hydroxyl groups.
5. Does the claim require a specific purification step?
No. The claim requires that D-α-amino acids are collected after conversion; it does not specify purification conditions or methods.
References
No external sources were provided with your prompt, and no patent document text beyond the claims you supplied can be reliably cited without adding unverifiable material.
