Protection Afforded by Maltosyl-β-cyclodextrin Against α-Chymotrypsin-Catalyzed Hydrolysis of a Luteinizing Hormone-Releasing Hormone Agonist, Buserelin Acetate.

Autor: Matsubara, Kazutaka, Ando, Yukihiro, Irie, Tetsumi, Uekama, Kaneto
Zdroj: Pharmaceutical Research; Oct1997, Vol. 14 Issue 10, p1401-1405, 5p
Abstrakt: Purpose. The present study addresses how maltosyl-β-cyclodextrin (G2-β-CyD) impacts upon the α-chymotrypsin-catalyzed hydrolysis of buserelin acetate, an agonist of luteinizing hormone-releasing hormone with emphasis upon the direct effect of G2-β-CyD on the activity of the protease. Methods. Kinetic and solubility studies were performed in isotonic phosphate buffer (pH 7.4) at 25°C and 37°C. The interaction of α-chymotrypsin with G2-β-CyD in the buffer solution was examined by differential scanning calorimetry. Results. G2-β-CyD decelerated the α-chymotrypsin-catalyzed hydrolysis of buserelin acetate to give the 1−3 tripeptide and the 4−9 hexapeptide fragments. This deceleration can be explained solely by a nonproductive encounter between a complex of the substrate with G2-β-CyD and the protease at relatively low CyD concentrations, while the direct inhibitory effect of G2-β-CyD on the proteolytic activity made a considerable contribution to the overall deceleration of the hydrolysis at higher CyD concentrations. Calorimetric studies indicate the presence of intermediate states in the thermal unfolding of α-chymotrypsin, simultaneously accompanied by the autolysis. By contrast, a two-state thermal unfolding of α-chymotrypsin was observed in the presence of G2-β-CyD, suggesting reduced proteolytic activity upon binding to G2-β-CyD. Conclusions. These results suggest that G2-β-CyD at higher concentrations inhibits the proteolytic action of α-chymotrypsin through direct interaction with the protease, as well as through the formation of a non-productive complex with the substrate. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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