Derivation of kinetic rate constant of enzyme-buffer mud cake clean up systems - Laboratory investigation and verification in high temperature fractured carbonate reservoir

2012 ◽  
Author(s):  
Bisweswar Ghosh ◽  
Mohamed Arif Mehtar ◽  
Debayan Ghosh ◽  
Bodhi Chaudhuri
Keyword(s):  
High Temperature ◽  
Laboratory Investigation ◽  
Rate Constant ◽  
Carbonate Reservoir ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
Mud Cake ◽  
Fractured Carbonate

scholarly journals Comparative kinetic study between native and chemically modified Cu,Zn superoxide dismutases

1993 ◽  
Vol 292 (2) ◽  
pp. 451-455 ◽  
Author(s):  
E Argese ◽  
R Girotto ◽  
E F Orsega
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Active Site ◽  
Electrostatic Force ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
K Value ◽  
Kinetic Behaviour ◽  
Pure Diffusion ◽  
Steering Mechanism

The kinetic behaviour of native bovine erythrocyte Cu,Zn superoxide dismutase (N-SOD) and of its derivatives by reaction with polyethylene glycol, acetic and succinic anhydrides has been investigated here in detail. Their responses to changes of pH and ionic strength (I) have been used as a probe for quantitatively displaying the relevance to kinetic rate constant of superficial positive charges driving the superoxide ion (O2-) toward the enzyme's active site. Overall kinetic trends indicate that this long-range O2- electrostatic guidance is essentially due to the positive charges of the amino-acid residues Lys-120 and Lys-134 which are strategically located around the active site. The comparison between the kinetic data obtained from N-SOD and those from polyethylene-glycolated SOD (PEG-SOD) enabled us to state that in PEG-SOD an O2(-)-steering positive electrostatic force, halved in comparison with N-SOD, is still operating, and that only Lys-120 is linked in the reaction of N-SOD with PEG. Elimination of the electrostatic driving force, carried out either by deprotonation of lysine amino groups at high pH, or by their neutralization with succinic anhydride and acetic anhydride, or by ionic screening at high ionic strength, always lowered the kinetic rate constant to a value of approx. 3 x 10(8) M-1.s-1. This value is about 15 times smaller than that measured in the presence of the reactant-steering mechanism and represents the k value of the reaction limited by pure diffusion. Finally, the kinetic behaviour of acetylated SOD and succinylated SOD demonstrated the inhibitor effect of OH- at strongly alkaline pH.

Solvation effect on kinetic rate constant of reactions in supercritical solvents

AIChE Journal ◽  
1998 ◽  
Vol 44 (3) ◽  
pp. 667-680 ◽  
Author(s):  
A. A. Chialvo ◽  
P. T. Cummings ◽  
Yu. V. Kalyuzhnyi
Keyword(s):  
Rate Constant ◽  
Solvation Effect ◽  
Kinetic Rate Constant ◽  
Kinetic Rate ◽  
Supercritical Solvents
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