title: Enzymatic activity and thermal stability of PEG-alpha-chymotrypsin conjugates.
abstract: Alpha-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.
authors.affiliation: Department of Chemistry, University of Puerto Rico-Río Piedras, PO Box 23346, San Juan, PR 00931-3346.
authors.forename: José A
authors.initials: JA
authors.lastname: Rodríguez-Martínez
authors.forename: Izarys
authors.initials: I
authors.lastname: Rivera-Rivera
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Solá
authors.forename: Kai
authors.initials: K
authors.lastname: Griebenow
mesh_terms: D000818:Animals; D002417:Cattle; D002918:Chymotrypsin / Q000737:chemistry* / Q000378:metabolism*; D004795:Enzyme Stability; D007700:Kinetics; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D013696:Temperature
chemical_list: D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D002918:Chymotrypsin; C117608:alpha-chymotrypsin