Химотрипсин

Химические свойства

Lyophilized powder, dialyzed

Использование

α-Chymotrypsin from bovine has been used in a study to inform proteasome inhibition in order to advance anticancer research. α-Chymotrypsin from bovine has also been used in a study that functionalized surface anchored poly(methylhydrosiloxane) thin films on oxidized silicon wafers.

Общее описание

Chymotrypsin (Chymar) is extractedfrom mammalian pancreas and is used in cataractsurgery. A dilute solution is used to irrigate the posteriorchamber of the eye to dissolve the fine filaments that holdthe lens.

Механизм действия

The general mechanism for chymotrypsin is the classic serine protease mechanism. Hydrolytic proteolysis by α-chymotrypsin begins with an initial nucleophilic attack on the peptide bond by Ser 195, activated by deprotonation by His 57. This leads to forming a tetrahedral intermediate, stabilized by the amide groups of Ser 195 and Gly 193. The subsequent collapse of this intermediate, assisted by protonation of the leaving group by His 57 and Asp 102, leads to an acyl-enzyme intermediate. Activation of a water molecule by His 57 and Asp 102 facilitates hydrolysis of this intermediate, resulting in the reformation of the catalytically active serine residue and the release of the product facilitated by protonation with His 57.

Методы очистки

α-Chymotrypsin is crystallised twice from four-tenths saturated ammonium sulfate solution, then dissolved in 1mM HCl and dialysed against 1mM HCl at 2-4o. The solution is stored at 2o [Lang et al. J Am Chem Soc 80 4923 1958].

использованная литература

[1] R J Schilling, A K Mitra. “Degradation of insulin by trypsin and alpha-chymotrypsin.” Pharmaceutical Research 8 6 (1991): 721–7.