Subunits triosephosphate isomerase

Subunit interface of triosephosphate isomerase site-directed mutagenesis and characterization of the altered enzyme, Biochemistry 1987, 26, 1258-1264. 

In the case of oligomeric proteins in which subunit contact regions have been revealed by X-ray crystallography34 353 or other methods described above,363 the equilibrium between oligomer and monomer can be changed by site-directed mutagenesis. For example, stable monomers of tyrosyl-tRNA synthetase were produced by a mutation of Phe-164 at the subunit interface to Asp, and it was revealed that the monomers are inactive and do not bind the substrate tyrosine.343 In the case of yeast triosephosphate isomerase, replacement of Asn-78 at the subunit interface did not cause dissociation of subunits under normal conditions.353 However, the stability of the enzyme was significantly lowered by the mutation, probably due to decreased subunit-subunit interaction.353... 

A major advancement is the elucidation of the structure of V. harveyi luciferase, at 2.4 A and 1.5 A resolution, " with key structural features summarized and discussed. Each subunit assumes a (P/a)g barrel structure, originally shown for the structure of triosephosphate isomerase (TIM). There are considerable structural similarities between the a and P subunits the main chains of these two subunits show good superposition."" The structure of V. harveyi luciferase Pj was also solved. " The four C-terminal residues (321-324) of P that are not resolved in the original aP structure were determined. In general, the secondary and tertiary structures of Pj are quite similar to those of ap. The intersubunit areas for P2 and aP are also similar, except that the former is smaller. The two subunits in Pj are highly homologous but not identical in structure the root-mean-square difference between the main P chains in P2 is 0.45 k7 A possible FMN site in P2 is discussed. 

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