Effect of the Covalent Modification with Poly(ethylene glycol) on α-Chymotrypsin Stability upon Encapsulation in Poly(lactic-co-glycolic) Microspheres

Castellanos, Ingrid J.; Al-Azzam, Wasfi; Griebenow, Kai

doi:10.1002/jps.20243

Cited by 55 publications

(65 citation statements)

References 38 publications

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“…There are several other reports of PLG microsphere release studies with proteins and peptides in the literature as summarized in Table II (15,16,(21)(22)(23)(24)(25)(26)(27). As noted, each example exhibited an initial burst release, followed by relatively little subsequent release.…”

Section: Benefits and Drawbacks Of Protein Delivery From Plg Depotsmentioning

confidence: 89%

“…The authors showed that even the lowest level of modification drastically reduced the amount of insoluble aggregates from 18% for the unmodified α-chymotrypsin to 4% (21). In vitro release profiles of unmodified and PEGylated-α-chymotrypsin were investigated and all formulations showed an initial burst within the first few days of incubation.…”

Section: Improving Delivery From Plg Depots Via Protein Pegylationmentioning

confidence: 99%

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Poly(ethylene glycol)-Modified Proteins: Implications for Poly(lactide-co-glycolide)-Based Microsphere Delivery

Pai

Tilton

Przybycien

2009

AAPS J

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Abstract. The reduced injection frequency and more nearly constant serum concentrations afforded by sustained release devices have been exploited for the chronic delivery of several therapeutic peptides via poly(lactide-co-glycolide) (PLG) microspheres. The clinical success of these formulations has motivated the exploration of similar depot systems for chronic protein delivery; however, this application has not been fully realized in practice. Problems with the delivery of unmodified proteins in PLG depot systems include high initial "burst" release and irreversible adsorption of protein to the biodegradable polymer. Further, protein activity may be lost due to the damaging effects of protein-interface and protein-surface interactions that occur during both microsphere formation and release. Several techniques are discussed in this review that may improve the performance of PLG depot delivery systems for proteins. One promising approach is the covalent attachment of poly(ethylene glycol) (PEG) to the protein prior to encapsulation in the PLG microspheres. The combination of the extended circulation time of PEGylated proteins and the shielding and potential stabilizing effects of the attached PEG may lead to improved release kinetics from PLG microsphere system and more complete release of the active conjugate.

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Section: Benefits and Drawbacks Of Protein Delivery From Plg Depotsmentioning

confidence: 89%

Section: Improving Delivery From Plg Depots Via Protein Pegylationmentioning

confidence: 99%

Poly(ethylene glycol)-Modified Proteins: Implications for Poly(lactide-co-glycolide)-Based Microsphere Delivery

Pai

Tilton

Przybycien

2009

AAPS J

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“…Lysozyme adsorption onto the surface of blank PLGA microspheres was thereby reduced when it was conjugated with methoxyPEG (mPEG, MW 5000) (Diwan et al, 2001). During PLGA microsphere degradation, as protein release is limited by protein adsorption onto the enlarged surface polymer area , protein chemical modification enhanced protein release rates as demonstrated for lysozyme (Diwan et al, 2001), interferon-α (Diwan et al, 2003) and α-chymotrypsin (Castellanos et al, 2005). However, the preferential location of surface-active pegylated protein on the surface of microspheres also increased burst release;…”

Section: Protein Chemical Modificationmentioning

confidence: 99%

“…an initial burst superior to 50% within the first day of incubation was induced by the covalent modification of α-chymotrypsin with PEG (Castellanos et al, 2005).…”

Section: Protein Chemical Modificationmentioning

confidence: 99%

How to achieve sustained and complete protein release from PLGA-based microparticles?

Giteau

Venier-Julienne

Aubert-Pouëssel

et al. 2008

International Journal of Pharmaceutics

234

184

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One of the most challenging tasks in the delivery of therapeutic proteins from PLGAbased microparticles is the sustained and complete release of the protein in its native form.The mechanisms responsible for incomplete protein release from these devices are numerous and complex; the beneficial effect of different formulations has often been evaluated in vitro.Strategies employed for overcoming protein destabilization during the release step are reviewed in this paper. Proteins have been protected in the deleterious environment by adding stabilizers to the formulation, or by modifying the protein or the polymer. Alternatively, some strategies have aimed at avoiding the formation of the destabilizing environment. As experimental conditions may influence the results from in vitro release studies, we initially report precautions to avoid adverse effects.

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“…Covalent modification of SBc with PEG was performed as previously described (Castellanos et al, 2005;Castillo et al, 2006). To obtain different levels of protein modification, molar ratios of 3.0, 6.0, and 9.0 of activated PEG-to-protein were used.…”

Section: Chemical Enzyme Modificationmentioning

confidence: 99%

Effect of PEG modification on subtilisin Carlsberg activity, enantioselectivity, and structural dynamics in 1,4‐dioxane

Castillo

Solá

Ferrer

et al. 2007

Biotech & Bioengineering

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The employment of enzymes as catalysts within organic media has traditionally been hampered by the reduced enzymatic activities when compared to catalysis in aqueous solution. Although several complementary hypotheses have provided mechanistic insights into the causes of diminished activity, further development of biocatalysts would greatly benefit from effective chemical strategies (e.g., PEGylation) to ameliorate this event. Herein we explore the effects of altering the solvent composition from aqueous buffer to 1,4-dioxane on structural, dynamical, and catalytic properties of the model enzyme subtilisin Carlsberg (SBc). Furthermore, we also investigate the effects of dissolving the enzyme in 1,4-dioxane through chemical modification with poly(ethylene)-glycol (PEG, M(W) = 20 kDa) on these enzyme properties. In 1,4-dioxane a 10(4)-fold decrease in the enzyme's catalytic activity was observed for the hydrolysis reaction of vinyl butyrate with D(2)O and a 50% decrease in enzyme structural dynamics as evidenced by reduced amide H/D exchange kinetics occurred. Attaching increasing amounts of PEG to the enzyme reversed some of the activity loss. Evaluation of the structural dynamic behavior of the PEGylated enzyme within the organic solvent revealed an increase in structural dynamics at increased PEGylation. Correlation analysis between the catalytic and structural dynamic parameters revealed that the enzyme's catalytic activity and enantioselectivity depended on the changes in protein structural dynamics within 1,4-dioxane. These results demonstrate the importance of protein structural dynamics towards regulating the catalytic behavior of enzymes within organic media.

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Effect of the Covalent Modification with Poly(ethylene glycol) on α-Chymotrypsin Stability upon Encapsulation in Poly(lactic-co-glycolic) Microspheres

Cited by 55 publications

References 38 publications

Poly(ethylene glycol)-Modified Proteins: Implications for Poly(lactide-co-glycolide)-Based Microsphere Delivery

Poly(ethylene glycol)-Modified Proteins: Implications for Poly(lactide-co-glycolide)-Based Microsphere Delivery

How to achieve sustained and complete protein release from PLGA-based microparticles?

Effect of PEG modification on subtilisin Carlsberg activity, enantioselectivity, and structural dynamics in 1,4‐dioxane

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