Partial Characterization of the Active Site of Carrot Poly(galacturonate) Hydrolase and Degradation of Oligo(D-galactosiduronates)

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Title:Partial Characterization of the Active Site of Carrot Poly(galacturonate) Hydrolase and Degradation of Oligo(D-galactosiduronates)
Creators:
Heinrichová, Kveta
Heinrich, Július
Dzúrová, Mária
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 60, 2, pp. 328-338

Abstract

<p>The dimension and arrangement of the active center in carrot poly(1→4-α-D-galacturonide)galacturonohydrolase (E.C.3.2.1.67) is studied. Molecular activities <i>k</i><sub>0 </sub>and parameters <i>k</i><sub>0</sub>/<i>K</i><sub>m</sub> were calculated from the experimentally determined Michaelis constants <i>K</i><sub>m</sub> and maximum rates of catalytic hydrolysis of linear oligo(D-galactosiduronates) (polymerization degree <i>n</i> = 2 to 7) at pH 5.0 and 30 °C. From the dependence of log <i>k</i><sub>0</sub> and log <i>k</i><sub>0</sub>/<i>K</i><sub>m</sub> on <i>n</i> we derived that the active center consists of six subsites, the catalytic site being situated between the first and second subsite. In accord with the theory of Hiromi [Hiromi K.: Biochem. Biophys. Res. Commun. <i>40</i>, 1 (1970)], the kinetic data were used for calculation of affinities (<i>A<sub>i</sub></i>) of the third (<i>A</i><sub>3</sub>) to the sixth (<i>A</i><sub>6</sub>) subsite. Two possible models were studied for the action of carrot poly(galacturonate)hydrolase which catalyzes the gradual terminal hydrolytic cleavage of oligo(D-galactosiduronates) from the non-reducing end of the molecule. The distribution of products in monomolecular hydrolysis of penta(D-galactosiduronate) under optimal conditions (pH and temperature) indicates a multi-chain enzymatic attack with predominant single collision. The kinetic results of the enzyme degradation are in good accord with the above-mentioned assumption.

Title:Partial Characterization of the Active Site of Carrot Poly(galacturonate) Hydrolase and Degradation of Oligo(D-galactosiduronates)
Creators:
Heinrichová, Kveta
Heinrich, Július
Dzúrová, Mária
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:60
Number:2
Page Range:pp. 328-338
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19950328UNSPECIFIED
ID Code:720
Item Type:Article
Deposited On:06 Feb 2009 17:03
Last Modified:06 Feb 2009 16:03

Citation

Heinrichová, Kveta; Heinrich, Július; Dzúrová, Mária (1995) Partial Characterization of the Active Site of Carrot Poly(galacturonate) Hydrolase and Degradation of Oligo(D-galactosiduronates). Collection of Czechoslovak Chemical Communications, 60 (2). pp. 328-338. ISSN 0010-0765

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