Isologous interactions

Isologous bonding is very important in oligomeric enzymes, and it has been suggested that isologous interactions evolved early. Initially there may not have been much complementarity in the bonding but two... 

Isoenzymes (isozymes) 536, 538 Isoionic point 106 Isolation of compounds 98-108 Isoleucine (He, I) 52s, 539 biosynthesis 540 branched fatty acids from 381 configuration 43 Isologous interactions 337-353 in oligomers 349 - 353 square 352s... 

Paired interactions. If two subunits are held together with interactions aj and are related by a twofold axis of rotation as shown in Fig. 7-11, we obtain an isologous dimer. Each point such as a in one subunit is related to the same point in the other subunit by reflection through the axis of rotation. In the center, along the twofold axis, points c and c are directly opposite the same points in the other subunit. Figure 7-11... 

Figure 7-22 Comparison of the interactions in isologous (dihedral) and heterologous (cyclic) square configurations of subunits.

In the isologous tetrahedron (Fig. 7-5) the third set of paired interactions cl must be taken into account. (However, the third interaction constant will not be an association constant of the type represented by Xfl AA and KhkAA but a dimensionless number.) On the other hand, the heterologous square has only a single interaction constant. 

Now consider the binding of one molecule of X to the isologous tetramer with a conformational change in one subunit (Eq. 7-44). We see that one pair of aj interactions and one pair of bk interactions have been... 

Multicellular system Interaction-induced differentiation of an ensemble of cells Isologous diversification in inter- and intradynamics Robustness in development... 

Figure 9.12. Subunit contacts in aspartate transcarbamoylase show heterologous contacts in the catalytic trimers, isologous contacts between regulatory dimers, and regulatory subunit-catalytic subunit interactions. See color insert.

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