Catalytic activity of enzyme in water/organic cosolvent mixtures for the hydrolysis of p-nitrophenyl acetate and p-nitrophenyl benzoate

نویسندگان

  • Santosh Kumar Verma
  • Kallol K Ghosh
  • Ravishankar Shukla
چکیده

The dependence of the catalytic activities of α-chymotrypsin on the concentration of organic cosolvents (acetonitrile, dimethyl sulfoxide, dimethyl formamide, ethylene glycol, methanol, ethanol, propan-2-ol and tert-butanol) in mixed aqueous media has been studied towards hydrolysis of p-nitrophenyl acetate and p-nitrophenyl benzoate using cetyltriphenylphosphonium bromide surfactant at pH 7.75. The temperature dependence hydrolysis of PNPA and PNPB catalyzed by α-chymotrypsin has also been reported. Under all the conditions employed, the reaction follows a Michaelis-Menten mechanism. The organic solvent influences the kcat and KM. The effect of polarity of solvent on the catalytic activity has been discussed. It is observed that the catalytic efficiency of α-chymotrypsin is enhanced in aqueous-organic media. Possible mechanism of micellar enzymology and the effect of organic co-solvents have been discussed.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

The kinetics of the alpha-chymotrypsin-catalyzed hydrolysis of p-nitrophenyl acetate in organic solvent-water mixtures.

The or-chymotrypsin-catalyzed hydrolysis of p-nitrophenyl acetate has been studied at pH 7 and 25’ in isopropyl alcoholwater and dioxane-water mixtures. It was found that the initial reaction in which the enzyme is acylated follows second order kinetics rather than Michaelis-Menten kinetics as previously reported. The second order rate constant for this reaction is markedly decreased by additio...

متن کامل

Phosphatase Hydrolysis of Organic Phosphorus Compounds

Phosphatases are diverse groups of enzymes that deserve special attention because of their significant roles in organic phosphorus (OP) mineralization to inorganic available forms (Pi). This work 1) compared the catalytic potentials of commercially acid phosphatase from wheat germ, sweet potato, and potato, and alkaline phosphatase from E. coli; 2) demonstrated that the rate of hydrolysis, cata...

متن کامل

Hydrolysis of 4-nitrophenyl acetate catalyzed by carbonic anhydrase III from bovine skeletal muscle.

We report three experiments which show that the hydrolysis of 4-nitrophenyl acetate catalyzed by carbonic anhydrase III from bovine skeletal muscle occurs at a site on the enzyme different than the active site for CO2 hydration. This is in contrast with isozymes I and II of carbonic anhydrase for which the sites of 4-nitrophenyl acetate hydrolysis and CO2 hydration are the same. The pH profile ...

متن کامل

Mechanisms of acylation of chymotrypsin by phenyl esters of benzoic acid and acetic acid.

The kinetics of the acylation of alpha-chymotrypsin by a series of substituted phenyl p-nitrobenzoates have been studied by stopped flow and conventional spectrophotometry. Electron withdrawal in the leaving group accelerates the rate of acylation, and the p value obtained for eight esters is +1.96. The pH- and pD-independent acylation rate constants are, respectively, 1.40 X 10(4) M-1S-1 and 1...

متن کامل

The hydrolysis of carbobenzoxy-L-tyrosine p-nitrophenyl ester by various enzymes.

cY-Chymotrypsin rapidly catalyzes the release of p-nitrophenol from carbobenzoxy-n-tyrosine p-nitrophenyl ester and the reaction has been made the basis of a spectrophotometric assay requiring only millimicrogram quantities of the crystalline enzyme (1). Other nitrophenyl esters, e.g. of acetic acid (2), hydrocinnamic acid (3), and carbobenzoxyglycine (4) are also hydrolyzed by chymotrypsin des...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2010