Allosteric regulation of aspartate transcarbamoylase. Changes in the sedimentation coefficient promoted by the bisubstrate analog N-(phosphonacetyl)-L-aspartate

Biochemistry ◽  
1977 ◽  
Vol 16 (23) ◽  
pp. 5077-5083 ◽  
Author(s):  
G. J. Howlett ◽  
H. K. Schachman
Keyword(s):  
Allosteric Regulation ◽  
Sedimentation Coefficient ◽  
Aspartate Transcarbamoylase

Further studies on aspartate transcarbamoylase: molecular weight of the c3r6 complex and analysis of succinate inhibition in the native enzyme

1976 ◽  
Vol 54 (12) ◽  
pp. 1061-1068
Author(s):  
William W.-C. Chan
Keyword(s):  
Molecular Weight ◽  
Competitive Inhibition ◽  
Gel Filtration ◽  
Frictional Coefficient ◽  
Sedimentation Coefficient ◽  
Native Enzyme ◽  
Aspartate Transcarbamoylase ◽  
Unusual Structure ◽  
Regulatory Subunits ◽  
Method Of Calculation

The complex which is formed when excess regulatory subunits (r2) of aspartate transcarbamoylase (EC 2.1.3.2) are added to a dilute solution of the catalytic subunit (c3) has been studied by gel-filtration on Sephadex G-200. The elution volume indicates a Stokes' radius of between 5.42 and 5.92 nm, depending on the method of calculation. Using the sedimentation coefficient of 7.7 S previously determined, the molecular weight is estimated to be close to 200 000, in support of the c3r6 structure proposed earlier for the complex. The calculated frictional coefficient indicates abnormal hydrodynamic properties which are probably due to unusual structure characteristics.The pattern of succinate inhibition of native aspartate transcarbamoylase has also been analyzed. At low concentrations, succinate activates the enzyme, presumably by converting it from the taut state to the relaxed (R) state. Further increase in the succinate concentration leads to competitive inhibition of the R state. Using a novel procedure for analysis of the data, the Michaelis constant for aspartate of the R state has been estimated to be about 7 mM. This value is close to the Km of c3r6 for aspartate, measured under identical conditions. The result therefore provides further evidence suggesting that the c3r6 complex resembles the R state of the native enzyme.

Allosteric regulation of aspartate transcarbamoylase. Analysis of the structural and functional behavior in terms of a two-state model

Biochemistry ◽  
1977 ◽  
Vol 16 (23) ◽  
pp. 5091-5099 ◽  
Author(s):  
G. J. Howlett ◽  
Michael N. Blackburn ◽  
John G. Compton ◽  
H. K. Schachman
Keyword(s):  
Allosteric Regulation ◽  
State Model ◽  
Aspartate Transcarbamoylase ◽  
Functional Behavior ◽  
Two State Model

New Paradigm for Allosteric Regulation of Escherichia coli Aspartate Transcarbamoylase

Biochemistry ◽  
2013 ◽  
Vol 52 (45) ◽  
pp. 8036-8047 ◽  
Author(s):  
Gregory M. Cockrell ◽  
Yunan Zheng ◽  
Wenyue Guo ◽  
Alexis W. Peterson ◽  
Jennifer K. Truong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Allosteric Regulation ◽  
Aspartate Transcarbamoylase ◽  
New Paradigm

scholarly journals Allosteric Regulation of Catalytic Activity:Escherichia coli Aspartate Transcarbamoylase versus Yeast Chorismate Mutase

2001 ◽  
Vol 65 (3) ◽  
pp. 404-421 ◽  
Author(s):  
Kerstin Helmstaedt ◽  
Sven Krappmann ◽  
Gerhard H. Braus
Keyword(s):  
Conformational Changes ◽  
Classical Model ◽  
Allosteric Regulation ◽  
Chorismate Mutase ◽  
Aspartate Transcarbamoylase ◽  
Detailed Knowledge ◽  
Wild Type ◽  
Function Relationship ◽  
Relationship Of ◽  
Entire Picture

SUMMARY Allosteric regulation of key metabolic enzymes is a fascinating field to study the structure-function relationship of induced conformational changes of proteins. In this review we compare the principles of allosteric transitions of the complex classical model aspartate transcarbamoylase (ATCase) from Escherichia coli, consisting of 12 polypeptides, and the less complicated chorismate mutase derived from baker's yeast, which functions as a homodimer. Chorismate mutase presumably represents the minimal oligomerization state of a cooperative enzyme which still can be either activated or inhibited by different heterotropic effectors. Detailed knowledge of the number of possible quaternary states and a description of molecular triggers for conformational changes of model enzymes such as ATCase and chorismate mutase shed more and more light on allostery as an important regulatory mechanism of any living cell. The comparison of wild-type and engineered mutant enzymes reveals that current textbook models for regulation do not cover the entire picture needed to describe the function of these enzymes in detail.

Allosteric regulation of GPCR Rhodopsin by soft matter

2020 ◽  
Author(s):  
Nipuna Weerasinghe ◽  
Steven Fried ◽  
Anna Eitel ◽  
Andrey Struts ◽  
Suchithranga Perera ◽  
...  
Keyword(s):  
Soft Matter ◽  
Allosteric Regulation
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