Thermodynamic nonideality as a probe of allosteric mechanisms: Preexistence of the isomerization equilibrium for rabbit muscle pyruvate kinase

Harris S.J. and Winzor D.J. (1988) Thermodynamic nonideality as a probe of allosteric mechanisms: Preexistence of the isomerization equilibrium for rabbit muscle pyruvate kinase. Archives of Biochemistry and Biophysics, 265 2: 458-465. doi:10.1016/0003-9861(88)90150-6


Author Harris S.J.
Winzor D.J.
Title Thermodynamic nonideality as a probe of allosteric mechanisms: Preexistence of the isomerization equilibrium for rabbit muscle pyruvate kinase
Journal name Archives of Biochemistry and Biophysics   Check publisher's open access policy
ISSN 1096-0384
Publication date 1988-01-01
Sub-type Article (original research)
DOI 10.1016/0003-9861(88)90150-6
Volume 265
Issue 2
Start page 458
End page 465
Total pages 8
Subject 1304 Biophysics
1303 Specialist Studies in Education
2700 Medicine
1312 Molecular Biology
Abstract Sedimentation velocity studies in the presence and absence of an inert space-filling solute, sucrose, have been used to establish preexistence of the isomerization equilibrium responsible for the allosteric behavior of rabbit muscle pyruvate kinase. Whereas the inclusion of phenylalanine (5 mm) with enzyme gives rise to a decrease of 0.3 S in the sedimentation coefficient of pyruvate kinase, the corresponding effect of phosphoenolpyruvate is to increase the sedimentation coefficient by 0.03 S. Consideration of these findings to signify the existence of an isomeric equilibrium between compact and expanded forms of the enzyme is substantiated by the finding that inclusion of sucrose (0.1 m) also brings about the change in sedimentation coefficient effected by phosphoenolpyruvate. By demonstrating that rabbit muscle pyruvate kinase undergoes isomerization in the absence of substrate, this study removes any necessity to consider the existence of an isomerization equilibrium that is substrate-induced; and thereby provides experimental support for adoption of the Monod model of allostery to interpret enzyme kinetic data for pyruvate kinase.
Q-Index Code C1
Institutional Status Unknown

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