The Unfolding Pathways of the Native and Molten Globule States of 5-aminolevulinate Synthase
Digital Object Identifier (DOI)
In this communication, we report the equilibrium and kinetic properties of the unfolding pathways of the native (pH 7.5) and alkaline molten globule (pH 10.5) states of the pyridoxal 5′-phosphate (PLP)-dependent enzyme 5-aminolevulinate synthase (ALAS). The stability of the molten globule state is adversely affected by thermal- and guanidine hydrochloride (GuHCl)-induced denaturation, and the equilibrium unfolding pathways, irrespective of pH, cannot be described with simple two-state models. Rapid kinetic measurements, in the presence of denaturing GuHCl concentrations, reveal that at pH 10.5, the rate of ALAS denaturation is 3 times faster than at pH 7.5. From pH jump experiments, comparable rates for the denaturation of the tertiary structure and PLP-microenvironment were discerned, indicating that the catalytic active site geometry strongly depends on the stable tertiary structural organization. Lastly, we demonstrate that partially folded ALAS tends to self-associate into higher oligomeric species at moderate GuHCl concentrations.
Was this content written or created while at USF?
Citation / Publisher Attribution
Biochemical and Biophysical Research Communications, v. 480, issue 3, p. 321-327
Scholar Commons Citation
Stojanovski, Bosko M.; Breydo, Leonid; Uversky, Vladimir N.; and Ferreira, Gloria C., "The Unfolding Pathways of the Native and Molten Globule States of 5-aminolevulinate Synthase" (2016). Molecular Medicine Faculty Publications. 297.