Substrate as a source of thermodynamic nonideality in enzyme kinetic studies: Invertase-catalyzed hydrolysis of sucrose

Shearwin K.E. and Winzor D.J. (1988) Substrate as a source of thermodynamic nonideality in enzyme kinetic studies: Invertase-catalyzed hydrolysis of sucrose. Archives of Biochemistry and Biophysics, 260 2: 532-539. doi:10.1016/0003-9861(88)90478-X


Author Shearwin K.E.
Winzor D.J.
Title Substrate as a source of thermodynamic nonideality in enzyme kinetic studies: Invertase-catalyzed hydrolysis of sucrose
Journal name Archives of Biochemistry and Biophysics   Check publisher's open access policy
ISSN 1096-0384
Publication date 1988-02-01
Sub-type Article (original research)
DOI 10.1016/0003-9861(88)90478-X
Open Access Status
Volume 260
Issue 2
Start page 532
End page 539
Total pages 8
Subject 1303 Specialist Studies in Education
1304 Biophysics
1312 Molecular Biology
Abstract Expressions for the effects of thermodynamic nonideality arising from the use of high concentrations of small substrate in enzyme kinetic studies are derived. Their application to experimental results for the hydrolysis of sucrose by yeast invertase (pH 4.9, 37 °C) signifies that the progressive decrease in initial velocity at high sucrose concentration is consistent with the occurrence of isomeric expansion during the transition of an enzyme-substrate complex to its activated state. Ultracentrifuge studies on the yeast enzyme preparation are then used to establish the physical acceptability of the volume change required to account for the kinetic effects in these terms: the postulated expansion of 1.3 liter/mol would represent a mere 0.16% increase in hydrated volume (or a corresponding increase in extent of asymmetry). Finally, although originally interpreted to signify an effect of sucrose on water concentration, published results for the invertase-sucrose system [J. M. Nelson and M. P. Schubert (1928) J. Amer. Chem. Soc.50, 2188-2193] also find a rational explanation in terms of the present analysis based on effects of thermodynamic nonideality in enzyme kinetic studies.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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