scholarly journals Simulation of an inhibitory equilibrium system. Aberrant proteinic target sizes as obtained by radiation inactivation

1984 ◽  
Vol 222 (1) ◽  
pp. 273-276 ◽  
Author(s):  
S Swillens
Keyword(s):  
Functional Unit ◽  
Target Size ◽  
Size Analysis ◽  
Equilibrium System ◽  
Reversible Binding ◽  
Radiation Inactivation

A model consisting of the reversible binding of an enzyme and a full inhibitor was theoretically studied. Radiation-inactivation experiments were simulated. Target-size analysis of the computer-generated data indicates that aberrant sizes much higher or much lower than the size of any component of the system may be obtained. Thus a target size larger than the sizes of the components of the system does not imply the existence of a multimeric functional unit of this size.

Radiation inactivation target-size analysis of soluble guanylate cyclase

1990 ◽  
Vol 1051 (3) ◽  
pp. 306-309 ◽  
Author(s):  
Shuichi Saheki ◽  
Takayoshi Kuno ◽  
Chikako Tanaka ◽  
Nozomu Takeuchi ◽  
Ferid Murad
Keyword(s):  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Target Size ◽  
Size Analysis ◽  
Radiation Inactivation

Estimation by radiation inactivation of the minimum functional size of acrosome-reaction-including substance (ARIS) in the starfish, Asterias amurensis

Zygote ◽  
1995 ◽  
Vol 3 (4) ◽  
pp. 351-355 ◽  
Author(s):  
Akira Ushiyama ◽  
Kazuyoshi Chiba ◽  
Akihiro Shima ◽  
Motonori Hoshi
Keyword(s):  
Acrosome Reaction ◽  
Functional Unit ◽  
Sugar Content ◽  
High Energy ◽  
Target Size ◽  
Minimum Size ◽  
Size Analysis ◽  
Asterias Amurensis ◽  
Total Sugar Content ◽  
Jelly Coat

SummaryIn the starfish Asterias amurensis, the jelly coat of the eggs contains a glycoprotein essential for the induction of the acrosome reaction in homologous spermatozoa that is termed the acrosome-reaction-inducing substance (ARIS).ARIS is a highly sulphated and fucose-rich glycoprotein of extremely high molecular mass(>104 kDa). ARIS was irradiated with high-energy eletrons in order to estimate the minimum size required for its biological activity. The minimum functional unit or target size of ARIS was estimated to be c. 14 kDa by target size analysis. ARIS was significantly disintegrated by the irradiation, yet the total sugar content was not apparently reduced. The binding of 125I-labelled ARIS to spermatozoa competed with that of irradiated ARIS, although the affinity of ARIS was much reduced after irradiation.

Target Size Analysis by Radiation Inactivation: The Use of Free Radical Scavengers

2005 ◽  
Vol 230 (7) ◽  
pp. 455-463 ◽  
Author(s):  
Gene C. Ness ◽  
Laura C. Pendleton ◽  
Michael J. McCreery
Keyword(s):  
Enzyme Activity ◽  
Free Radical ◽  
Functional Unit ◽  
Radical Scavenging ◽  
Free Radical Scavenging ◽  
Target Size ◽  
Free Radical Scavengers ◽  
Radical Scavengers ◽  
Radiation Inactivation ◽  
Glucose 6 Phosphate Dehydrogenase

Several model systems were employed to assess indirect effects that occur in the process of using radiation inactivation analysis to determine protein target sizes. In the absence of free radical scavengers, such as mannitol and benzoic acid, protein functional unit sizes can be drastically overestimated. In the case of glutamate dehydrogenase, inclusion of free radical scavengers reduced the apparent target size from that of a hexamer to that of a trimer based on enzyme activity determinations. For glucose-6-phosphate dehydrogenase, the apparent target size was reduced from a dimer to a monomer. The target sizes for both glutamate dehydrogenase and glucose-6-phosphate dehydrogenase in the presence of free radical scavengers corresponded to subunit sizes when determinations of protein by sodium dodecyl sulfate–polyacrylamide gel electrophoresis or immunoblotting were done rather than enzyme activity. The free radical scavengers appear to compete with proteins for damage by secondary radiation products, since irradiation of these compounds can result in production of inhibitory species. Addition of benzoic acid/mannitol to samples undergoing irradiation was more effective in eliminating secondary damage than were 11 other potential free radical scavenging systems. Addition of a free radical scavenging system enables more accurate functional unit size determinations to be made using radiation inactivation analysis.

scholarly journals Size determination of an equilibrium enzymic system by radiation inactivation: theoretical considerations

1982 ◽  
Vol 205 (3) ◽  
pp. 477-483 ◽  
Author(s):  
P Simon ◽  
S Swillens ◽  
J E Dumont
Keyword(s):  
Enzyme Activity ◽  
Numerical Data ◽  
Radiation Energy ◽  
Target Size ◽  
Molecular Organization ◽  
Size Analysis ◽  
Radiation Inactivation ◽  
Theoretical Considerations ◽  
Regulation Of Enzyme Activity

Radiation inactivation of complex enzymic systems is currently used to determine the enzyme size and the molecular organization of the components in the system. We have simulated an equilibrium model describing the regulation of enzyme activity by association of the enzyme with a regulatory unit. It is assumed that, after irradiation, the system equilibrates before the enzyme activity is assayed. Our theoretical results show that the target-size analysis of these numerical data leads to a bad estimate of the enzyme size. Moreover, some implicit assumptions such as the transfer of radiation energy between non-covalently bound molecules should be verified before interpretation of target-size analysis. It is demonstrated that the apparent target size depends on the parameters of the system, namely the size and the concentration of the components, the equilibrium constant, the relative activities of free enzyme and enzymic complex, the existence of energy transfer, and the distribution of the components between free and bound forms during the irradiation.

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