Synthesis, isolation, and characterization of conjugates of ovalbumin with monomethoxypolyethylene glycol using cyanuric chloride as the coupling agent

Jackson, Chung-Ja C.; Charlton, James L.; Kuzminski, Kimberly; Lang, Glen M.; Sehon, A.H.

doi:10.1016/0003-2697(87)90208-9

Cited by 85 publications

(45 citation statements)

References 28 publications

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“…The same thickness is expected for the amino-PEG-PE. Finally, PEG is known to shield charges when it is attached to proteins [23] or liposomes [21]. This is expected to nullify, at least partially, the polar head group charges underneath the polymer.…”

Section: Resultsmentioning

confidence: 99%

Long circulating, cationic liposomes containing amino‐PEG‐phosphatidylethanolamine

Zalipsky¹,

Brandeis²,

Newman³

et al. 1994

FEBS Letters

100

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Ah&actLigand attachment to polyethylene glycol (PEG) grafted, long circulating liposomes at the polymer terminus is of interest for targeting but the effect of positively charged groups is unknown. Amino-polyethylene glycol-phosphatidylethanolamine (AminoPEG-PE), prepared in four steps from a-amino-o+hydroxy-PEG, was tested for intluence on liposome interactions in vivo: blood circulation and biodistribution. Despite surface amines on each liposome conferring cationic behavior, in vivo properties are comparable to those obtained with methoxy-PEG-PE. The consequences are profound for targeting and possibly systemic delivery of cationic lipidic-polynucleotide complexes.

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Section: Resultsmentioning

confidence: 99%

Long circulating, cationic liposomes containing amino‐PEG‐phosphatidylethanolamine

Zalipsky¹,

Brandeis²,

Newman³

et al. 1994

FEBS Letters

100

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“…Previous studies with PEG, or PEG derivatives, coupled to purified proteins have demonstrated that the protein half-life within the circulation is greatly improved (5,6,8). Similarly, liposomes containing externally disposed PEG lipids have improved half-lives in vivo (33)(34)(35).…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, liposomes containing externally disposed PEG lipids have improved half-lives in vivo (33)(34)(35). It is also of interest that the covalent attachment of PEG usually does not impair the function of purified enzymes and appears to make foreign proteins nonimmunogenic even after repetitive intravenous administration (5,6,8,(36)(37)(38)(39). The ''camouflage'' effected by PEG is imparted by the special physico-chemical nature of PEG (i.e., its size, large exclusion volume, and extensive hydration), which may prevent the interactions of large molecules such as antibodies with RBC and may as well hinder cell-cell interactions.…”

Section: Discussionmentioning

confidence: 99%

“…The general protocol for mPEG derivatization of intact RBC was based on that previously developed for covalent modification of proteins with cyanuric chloride-coupled PEG (8,9). mPEG (M r 5 kDa) conjugated to cyanuric chloride was added to washed RBC suspended to a hematocrit of Ϸ12% in isotonic alkaline phosphate buffered saline (PBS; 50 mM K 2 HPO 4 ͞105 mM NaCl, pH Ϸ9.2) and the RBC were incubated for 30 min at 4°C.…”

Section: Methodsmentioning

confidence: 99%

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Chemical camouflage of antigenic determinants: Stealth erythrocytes

Scott

Murad

Koumpouras

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

207

215

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In a number of clinical circumstances it would be desirable to artificially conceal cellular antigenic determinants to permit survival of heterologous donor cells. A case in point is the problem encountered in transfusions of patients with rare blood types or chronically transfused patients who become allosensitized to minor blood group determinants. We have tested the possibility that chemical modification of the red blood cell (RBC) membrane might serve to occlude antigenic determinants, thereby minimizing transfusion reactions. To this end, we have covalently bound methoxy(polyethylene glycol) (mPEG) to the surface of mammalian RBC via cyanuric chloride coupling. Human RBC treated with this technique lose ABO blood group reactivity as assessed by solution-phase antisera agglutination. In accord with this, we also find a profound decrease in anti-blood group antibody binding. Furthermore, whereas human monocytes avidly phagocytose untreated sheep RBC, mPEG-derivatized sheep RBC are ineffectively phagocytosed. Surprisingly, human and mouse RBC appear unaffected by this covalent modification of the cell membrane. Thus, mPEG-treated RBC are morphologically normal, have normal osmotic fragility, and mPEG-derivatized murine RBC have normal in vivo survival, even following repeated infusions. Finally, in preliminary experiments, mPEG-modified sheep RBC intraperitoneally transfused into mice show significantly improved (up to 360-fold) survival when compared with untreated sheep RBC. We speculate that similar chemical camouf lage of intact cells may have significant clinical applications in both transfusion (e.g., allosensitization and autoimmune hemolytic disease) and transplantation (e.g., endothelial cells and pancreatic ␤ cells) medicine.The transfusion of red blood cells (RBC) is the most common, and best tolerated, form of tissue transplantation. Indeed, in 1993, over 14 million units of blood were donated for transfusion in the United States alone (1). In most transfusions, simple blood typing (ABO͞Rh-D) is sufficient to identify appropriate donors. Occasionally, however, appropriate donors for patients with rare blood types cannot quickly be found; a situation that may become life-threatening. More often, problems are encountered in individuals who receive chronic transfusions, such as patients with sickle cell anemia and thalassemia. In such patients, alloimmunization against minor RBC antigens can make it nearly impossible to identify appropriate blood donors (2-4). Previous studies in which purified proteins were covalently modified with poly(ethylene glycol) (PEG) provided a possible solution to this problem. PEG-modified proteins have been shown to have increased in vivo survival and to be nonimmunogenic, even with repeated infusions (5, 6). We therefore explored the hypothesis that the covalent binding of PEG to intact RBC might mask RBC surface antigens and thereby permit the survival of heterologous or even xenogeneic RBC.To experimentally test this hypothesis, human, mouse, and sheep RBC were...

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“…However, it can form hexamers in elution buffer (Pritsa and Kyriakidis, 2001). Due to the strong hydrophilici ty of mPEG-ALD 20000 , the apparent molecular weight is higher than the actual molecular weight in the mobile phase buffer (Jackson et al, 1987). L-ASNase eluted later than PEGylated L-ASNase (Fig.…”

Section: Discussionmentioning

confidence: 98%

A PEGylation Technology of L-Asparaginase with Monomethoxy Polyethylene Glycol-Propionaldehyde

Wang

Cao

Chi

et al. 2012

Zeitschrift Für Naturforschung C

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Polyethylene glycol (PEG) conjugation technology has been successfully applied to improve the performance of protein drugs. In this study, L-asparaginase was N-terminal sitespecifi cally modifi ed by alkylating PEG with monomethoxy polyethylene glycol-propionaldehyde (mPEG-ALD 20000 ). The optimum reaction parameters were determined as pH 5.0, a molar ratio of mPEG-ALD 20000 to L-asparaginase of 10:1, a reaction time of 16 h and temperature of 25 °C. PEG-L-asparaginase (PEG-L-ASNase) was isolated and purifi ed with consecutive anion-exchange (XK, 16 × 20 cm, Q Sepharose FF) and gel-fi ltration (Tricorn, 10 × 600 cm, Sephacryl S-300 HR) chromatography, respectively. PEG-L-ASNase retained 43.5% of its activity and the N-terminal amino groups were modifi ed to an extent of 3.67%.

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Synthesis, isolation, and characterization of conjugates of ovalbumin with monomethoxypolyethylene glycol using cyanuric chloride as the coupling agent

Cited by 85 publications

References 28 publications

Long circulating, cationic liposomes containing amino‐PEG‐phosphatidylethanolamine

Long circulating, cationic liposomes containing amino‐PEG‐phosphatidylethanolamine

Chemical camouflage of antigenic determinants: Stealth erythrocytes

A PEGylation Technology of L-Asparaginase with Monomethoxy Polyethylene Glycol-Propionaldehyde

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