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The conformational stability of Plasmodium falciparum triosephosphate isomerase (TIMWT) enzyme was studied in urea and guanidinium chloride (GdmCl) solutions by circular dichroism, fluorescence and size-exclusion chromatography. The dimeric enzyme was observed to be stable in urea solutions. It retained a substantial secondary, tertiary and quaternary structure even in 8 M urea. On the other hand, the unfolding transition was completed by 2.5 M GdmCl.

The functional orientation of the acyltransferase (AT) domain was examined by inactivating the AT domain of module2 through site-directed mutagenesis utilizing a bimodular derivative of the 6-deoxyerythronolide B synthase. Both the inactivated AT domain of module 2 polypeptide and the inactive ketosynthase protein were found to promote polyketide synthesis, indicating that AT2 may function from either subunit. The results further indicated that the two clusters of active sites may simultaneously use the AT domain within the same dimeric module.

A three-step procedure was used for the purification of a modular polyketide synthase (PKS) of erythromycin, 6-deoxyerythronolide B synthase (DEBS). The characterization of one of its bimodular derivative that is composed of two modules of DEBS and a thioesterase domain, DEBS 1+TE, revealed that it possesses high catalytic competence, allowing a high rate of steady-state synthesis of triketide lactone 2. Cross-linking studies, on the other hand, confirmed that DEBS modules are dimeric in nature and that other functional groups like amines and thiols can be found within the dimeric module.

The mechanisms of urea- and guanidinium chloride-induced protein unfolding of the dimeric enzyme thymidylate synthase were investigated by far- and near-UV circular dichroism and intrinsic tryptophan fluorescence spectroscopy. The results revealed remarkable differences in the unfolding profiles of the proteins, which were attributed to the stability of the small structural domain in the active site. The rate of protein unfolding was observed to proceed rapidly under denaturant conditions which promote dissociation and loss of structure.

The remarkable substrate tolerance of the fatty acyl-CoA ligases (FACLs) to produce diverse acyl-CoAs and N-acetylcysteamine (NAC) analogues from their corresponding acids is reported. The acyl-activating enzymes (AAE) proteins provide an attractive route to expand the precursors available for polyketide biosynthesis.

Polyketides, which have a broad range of uses in human therapy, animal health and agriculture, have been known to be synthesized by using expensive coenzyme A thioesters used for chain extension. Large scale production of polyketides is therefore not economically feasible with the present method. A new truncated MeMalCoA derivative was synthesized in just one step and subsequently efficiently used as a substrate analogue by a module of the deoxyerythronolide-B synthase protein complex to produce a polyketide.