Enzyme binding, influence

The catalytic role of the enzyme is influenced by the metal ion in the active site of the proteins and the binding mode of the ligands to this metal ion, and the study of this influence is the main theme of the present monograph. The catalytic... 

Another approach towards immobilization via ionic interactions is the use of tethered metal ions, such as Cu, Co, or Ni, in order to bind the enzyme [53, 54]. This is particularly so when the enzyme contains an easily accessible imidazole residue from histidine [55] or a His tag (Figure 2.6) [56-59], that is a short tag with six histidines. This tag can be readily introduced by genetically modifying the enzyme. Little influence of the tag on the catalytic performance has been noticed. When benzaldehyde lyase [60] was immobilized on an Ni -containing polyvinylpyrrolidinone-based matrix, it could be reused several times for the formation of benzoin (12) (Scheme 2.4) [58]. 

Jayatilleke P, Nair A, Zauhar R, Welsh WJ. Computational studies on HIV-1 protease inhibitors Influence of calculated inhibitor-enzyme binding affinities on the statistical quality of 3D-QSAR Models. J Med Chem 2000 43 4446. 

Only one coordination isomer is likely to be the true substrate in the active site of an enzyme. The reason for expecting this to be so is that it is almost certain that only one transition state is involved in a given step of an enzymic reaction, and the structure of this transition state will be strongly influenced by enzymic binding interactions. These binding interactions will manifest themselves in the ground states of complexes such as E-MgATP. They will tend to... 

Geometric orientation of the acylsulfamoyl benzoxaborole group was not found to substantially influence inhibitory activity (29 vs. 30, 31 vs. 32). This finding is consistent with the shallow enzyme binding pocket utilizing a number of relatively weak interactions. Along these lines, two distinct cyclization modes (P1-P3 and P2-P4) and many amino acid replacements could be accommodated. The P2-P4 (29 and 30) and P1-P3 (31 and 32) inhibitors were essentially equipotent, indicating that both macrocyclization modes are effective when individual residues were also optimized for each P1-P3 and P2-P4 motif. 

This means that the methods developed for the calculation of physicochemical effects can also be used to deepen our understanding of biochemical rcaaions. Clearly, electronic effects within the substrate molecule arc not the only ones determining its reactivity, The binding of the substrate to the enzyme is also influenced... 

In such inhibition, the inhibitor and die substrate can simultaneously bind to the enzyme. The nature of the enzyme-inhibitor-substrate binding has resulted in a ternary complex defined as EIS. The Ks and Kt are identical to the corresponding dissociation constants. It is also assumed that the EIS does not react further and is unable to deliver any product P. The rate equation for non-competitive inhibition, unvAX, is influenced ... 

There has been considerable discussion regarding the mode of action of the sea cucumber and starfish saponins. Both the triterpene and steroidal glycosides inhibit both Na/K ATPase and Ca/Mg ATPase 06) possibly as a result of their aglycone structures. However, their detergent properties cause membrane disruption which will influence the activity of membrane-bound enzymes such as the ATPases. In investigating the actions of saponins on multilamellar liposomes, it was found that cholesterol serves as the binding site for such saponins and that cholesterol-free lip-somes are not lysed by saponins 107). 

ZAHNLEY J c (1984) Stability of enzyme inhibitors and lectins in foods and the influence of specific binding interactions. Adv Exp Med Biol. 177 333-65. 

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