Complexes of polyelectrolytes with the enzymes pepsin and α‐chymotrypsin

Abstract

It was shown that both the enzymes pepsin and a-chymotrypsin will displace the anionic dye Eosin Y from complexes of the dye with the polycations protamine or polybrene. The dyerelease was monitored fluorimetrically and was found to be strongly time-dependent. At equilibrium, pepsin released all the bound dye from both polycation-dye complexes when the mole ratio of pepsin to base moles of polycation were 1 : 10 for protamine and 1 : 13 for polybrene. a-Chymotrypsin did not release all the bound dye, but appeared to form definite complexes with the polycations. The existence of the complexes between the enzymes and the polycations was correlated with the fact that the polycations are inhibitors of the enzymes. Additionally, it has been shown that pepsin releases Acridine Orange (AO) from a poly(viny1 sulfate) (PVS)-A0 complex. The mole ratio of pepsin to base moles of PVS was found to be 1 : 2,5. Cooperative binding constants were also evaluated for each dye-polyion system.

Enzyme-polyelectrolyte noncovalent complexes as catalysts for reactions in binary mixtures of polar organic solvents with water

“…Formation of enzymepolybrene complexes was proved by experiments with a fluorescent molecule, eosin (Lawton and Mekras, 1985). Fluorescence of eosin is known to be quenched by noncovalent binding to polycations.…”

“…Aqueous solution ofpolybrene, 0.35 mg-m1-1, in 5 mM MOPS buffer, pH 7.45, was added by 10 BI portions (the total volume added did not exceed 100 gl) to eosin 5-isothiocyanate (Sis_,ma, E 2005, further reffered to as eosin) solution, 2 ml, 10 BM, in 5 mM MOPS buffer, pH 7.45 or corresponding water-ethanol mixture, until fluorescence intensity no longer decreased. The excitation wavelength was 515 nm~ the emission was measured at 540 nm Complete quenching of eosin fluorescence by polybrene indicated that aH sites for eosin binding in the polymer molecule were occupied by molecules of the dye (Lawton and Mekras, 1985). Aqueous solution ofpolybrene-eosin complex where eosin fluorescence was completely quenched (10 ml), was further divided into 10 portions of equal volume.…”