Abstract
α-Chymotrypsin was chemically modified with methoxypoly(ethylene glycol) (PEG) of different molecular weights (700, 2,000, and 5,000 Da) and the amount of polymer attached to the enzyme was varied systematically from 1 to 9 PEG molecules per enzyme molecule. Upon PEG conjugation, enzyme catalytic turnover (k cat) decreased by 50% and substrate affinity was lowered as evidenced by an increase in the K M from 0.05 to 0.19 mM. These effects were dependent on the amount of PEG bound to the enzyme but were independent of the PEG size. In contrast, stabilization toward thermal inactivation depended on the PEG molecular weight with conjugates with the larger PEGs being more stable.
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Acknowledgments
This publication was made possible by grant number S06 GM08102 from the National Institute for General Medical Sciences (NIGMS) at the National Institutes of Health (NIH) through the Support of Competitive Research (SCORE) Program. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIGMS. JARM was supported by a fellowship from the NIH Research Initiative for Scientific Enhancement (RISE) Program (R25 GM061151) and by the Fellowship Program of the Puerto Rico Development Company (PRIDCO). IRR was supported by NIH-MARC fellowship (T34 GM061151). The authors would like to thank Héctor R. Cintrón-Colón for helping in performing enzyme kinetic measurements.
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Rodríguez-Martínez, J.A., Rivera-Rivera, I., Solá, R.J. et al. Enzymatic activity and thermal stability of PEG-α-chymotrypsin conjugates. Biotechnol Lett 31, 883–887 (2009). https://doi.org/10.1007/s10529-009-9947-y
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DOI: https://doi.org/10.1007/s10529-009-9947-y