Heat of PPi hydrolysis varies depending on the enzyme used. Yeast and corn vacuolar pyrophosphatase.
With yeast-soluble inorganic pyrophosphatase, the heat released during PP(i) hydrolysis was -6.3 kcal/mol regardless of the KCl concentration in the medium. With the membrane-bound pyrophosphatase of corn vacuoles, the heat released varies between -23.5 and -7.5 kcal/mol depending on the KCl concentration in the medium and whether or not a H(+) gradient is formed across the vacuole membranes. The data support the proposal that enzymes are able to handle the energy derived from phosphate compound hydrolysis in such a way as to determine the parcel that is used for work and the fraction that is converted into heat.
da-Silva
Wagner S
WS
Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro RJ, 21941-590, Brasil.
Bomfim
Flavio M
FM
Galina
Antonio
A
de Meis
Leopoldo
L
D002384:Catalysis; D011756:Diphosphates / Q000378:metabolism*; D006358:Hot Temperature; D006868:Hydrolysis; D011755:Pyrophosphatases / Q000502:physiology*; D014617:Vacuoles / Q000201:enzymology*; D015003:Yeasts / Q000201:enzymology*; D003313:Zea mays / Q000201:enzymology*
D011756:Diphosphates; D011755:Pyrophosphatases