Pressure denaturation of phosphorylating glyceraldehyde-3-phosphate dehydrogenase from Bacillus stearothermophilus

The effects of hydrostatic pressure on apo wild-type glyceraldehyde-3-phosp hate dehydrogenase (wtGAPDH) from Bacillus stearothermophilus (B. stearothe rmophilus) have been studied by fluorescence spectroscopy under pressure fr om 0.1 to 650 MPa. Unlike yeast GAPDH [Ruan, K. C., and Weber, G. (1989) Bi ochemistry 28, 2144-2153], denaturation of the tetrameric apo wtGAPDH from B. stearothermophilus is likely to precede dissociation into subunits. As e xpected, denaturation is accompanied by the loss of enzymatic activity. B. stearothermophilus apo wtGAPDH interfaces are less pressure sensitive than apo yeast GAPDH ones, while NAD does not protect B. stearothermophilus wtGA PDH against denaturation by pressure. The pressure effects on B. stearother mophilus GAPDH whose R and Q-axis interfaces were destabilized by disruptio n of interfacial hydrogen bonds are similar to that of apo wtGAPDH. (C) 200 1 Academic Press.