Charge neutralization in the active site of the catalytic trimer of aspartate transcarbamoylase promotes diverse structural changes.

ABSTRACT: A classical model for allosteric regulation of enzyme activity posits an equilibrium between inactive and active conformations. An alternative view is that allosteric activation is achieved by increasing the potential for conformational changes that are essential for catalysis. In the present study, substitution of a basic residue in the active site of the catalytic (C) trimer of aspartate transcarbamoylase with a non-polar residue results in large interdomain hinge changes in the three chains of the trimer. One conformation is more open than the chains in both the wild-type C trimer and the catalytic chains in the holoenzyme, the second is closed similar to the bisubstrate-analog bound conformation and the third hinge angle is intermediate to the other two. The active-site 240s loop confo

SUBMITTER: Endrizzi JA 

PROVIDER: S-EPMC5654843 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature