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Conjugation of polysialic acid to biologics in glycoengineered Escherichia coli

Award Information

Department of Health and Human Services
Award ID:
Program Year/Program:
2010 / SBIR
Agency Tracking Number:
Solicitation Year:
Solicitation Topic Code:
Solicitation Number:
Small Business Information
33 Thornwood Drive ITHACA, NY -
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Woman-Owned: No
Minority-Owned: No
HUBZone-Owned: No
Phase 1
Fiscal Year: 2010
Title: Conjugation of polysialic acid to biologics in glycoengineered Escherichia coli
Agency: HHS
Contract: 1R43GM093483-01
Award Amount: $199,020.00


DESCRIPTION (provided by applicant): Biotherapeutics currently constitute a 70 billion market, but their clinical efficacy is often compromised by limitations arising from proteolytic degradation, uptake by cells of the reticuloendothelial system, renal r emoval, and immunocomplex formation. This can lead to difficulties in reaching and maintaining effective therapeutic concentrations in the blood. The most popular approach to lengthen the active life of a protein therapeutic has been conjugation to polyeth yleneglycol (PEGylation). However, PEG is not eliminated via normal detoxification mechanisms in the body and the administration of PEGylated proteins can even generate anti-PEG antibodies. An emerging alternative to PEGylation is polysialylation which inv olves attachment of polymers of polysialic acid (PSA) to a protein. PSA is being developed for clinical use and polysialylated versions of insulin and erythropoietin have displayed improved tolerance and pharmacokinetics. PSA is synthesized in the body on neural cell adhesion molecule and, unlike PEG, is metabolized as a natural sugar molecule by sialidases. Unfortunately, as with PEGylation, the PSA conjugation process is technically complex and expensive. The multi-step, in vitro process of PSA conjugatio n is further complicated by the fact that standard chemical conjugation of PSA results in products with random attachment patterns and undesirable heterogeneity. Glycobia specializes in glycoengineering bacteria for use as an expression platform for the st ereospecific biosynthesis of therapeutic glycoproteins. The specific hypothesis behind the current proposed studies is that glycoengineered E. coli can be used to produce PSA-conjugated proteins in a single fermentation without the need for in vitro chemic al modification. Based on these observations, the objective of this proposal is to generate PSA-conjugated recombinant protein in glycoengineered E. coli by: cloning and expressing the genetic machinery for PSA synthesis in glycoengineered E. coli (Aim1) a nd conjugating PSA to recombinant human insulin in the periplasm of glycoengineered E. coli (Aim 2). Such an expression platform will represent a stereospecific, directed, rapid, and cost-effective process for the production of PSA-conjugated biotherapeuti cs that will bring the production process of PSA-conjugated proteins in concert with their tremendous therapeutic potential. PUBLIC HEALTH RELEVANCE: The efficacy of protein drugs is often compromised by premature elimination from the blood, which r esults in unacceptably short therapeutic windows and costs that are prohibitive to the healthcare consumer. The chemical attachment of polysialic acid to therapeutic proteins results in improved tolerance and pharmacokinetics, but the process of polysialic acid conjugation is technically challenging and expensive. These proposed studies focus on producing polysialic acid-conjugated proteins in Escherichia coli fermentation without the need for in vitro chemical modification.

Principal Investigator:

Adam C. Fisher

Business Contact:

Adam Fisher
Small Business Information at Submission:


EIN/Tax ID: 126411006
Number of Employees: N/A
Woman-Owned: No
Minority-Owned: No
HUBZone-Owned: No