Invalidity dossier
US 5612460
Active carbonates of polyalkylene oxides for modification of polypeptides
Current assignee: Viskase Holdings Inc
Added 9/23/2026, 9:23:37 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US 5,612,460 A
Title: Active carbonates of polyalkylene oxides for modification of polypeptides
Patent number: US 5,612,460 A
Application number: US 08/198,193
Inventor: Shmuel Zalipsky
Original assignee: Enzon Inc. (current assignee listed: Enzon Pharmaceuticals Inc)
Priority date: 1989-04-19 (priority claimed from US 07/511,243, which issued as US 5,122,614)
Filing date: 1994-02-17
Publication (grant) date: 1997-03-18
Legal status as listed: Expired – Lifetime (anticipated expiration 2014-03-18)
Purpose (from the supplied text): The patent concerns active carbonates of poly(alkylene oxides) — particularly polyethylene glycol (PEG) — used to modify polypeptides and proteins. The abstract describes preparation methods and hydrolysis behavior of these carbonate derivatives.
Plain-language scope (based only on the supplied text): The disclosure relates to reagents in which a polyalkylene oxide (notably PEG) is joined through a carbonate linkage to an activating group, and to reacting such reagents with amino groups on polypeptides/proteins to form modified proteins. The text associates the subject matter with carbamic acid/ethyl carbamate chemistry, carbonate and chloroformate compounds, phosgene, N-hydroxysuccinimide, and oxycarbonyl functional groups, and with example proteins/enzymes including trypsin, arginase, glutaminase, adenosine deaminase, asparaginase, chymotrypsin, and bovine serum albumin. Reactions are described in aqueous buffer, with triethylamine, and with analytical methods such as titration, HPLC, and 13C NMR. However, the excerpt as supplied does not reproduce the actual claims, so the precise claim scope cannot be stated.
What the excerpt does not establish: Since the excerpt does not include the full claim text, specification, or drawings, I cannot state the exact claimed compounds, methods, or limitations, nor any measured results or quantitative data. It also does not establish inventorship details beyond the listed inventor, the accuracy of assignee listings, or the legal status stated by the source.
Generated 10/1/2026, 9:34:18 PM
Cases on file (0)
Specific litigation cases in our database that name US patent 5612460. The free-form analysis below may also discuss cases beyond this list.
No cases on file mention this patent. Upload a CSV or add a case manually in Admin → Manage litigation cases.
Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.