title: The effects of pressure on yeast cytochrome c peroxidase.
abstract: The effects of pressure on cytochrome c peroxidase [CcP(FeIII)], its cyano derivative (CcP X CN) and its enzyme-substrate complex (ES) have been studied. The effects of pressure on the binding of the substrate analog porphyrin cytochrome c (porphyrin c) to CcP X CN and ES have also been studied. High pressure causes CcP(FeIII) to undergo a high-spin to low-spin transition but has no detectable effect on either CcP X CN, which is already low spin, or on ES. The low-spin CcP(FeIII) structure at pressure is similar to the low-spin form at low temperature and the low-spin form of horseradish peroxidase at high pressure. delta V degree associated with the spin equilibrium is about 30 ml/mol and is independent of temperature. delta G degree is small, 4.7 kJ/mol at 0 degree C, while delta H degree is 14.2 kJ/mol at 1 bar (100 kPa). Pressure has no detectable effect on the binding equilibria of mixtures of CcP X CN plus porphyrin c or ES plus porphyrin c. This indicates that the interaction of CcP and porphyrin c results in little or no volume change; the same is true in the case of cytochrome c oxidase and porphyrin c.
mesh_terms: D003578:Cytochrome-c Peroxidase / Q000378:metabolism*; D010544:Peroxidases / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism; D011312:Pressure; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D011166:Porphyrins; C033886:porphyrin c; D010544:Peroxidases; D003578:Cytochrome-c Peroxidase