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.
Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Cidade Universitária, Rio de Janeiro RJ, 21941-590, Brasil.
Wagner S
WS
da-Silva
Flavio M
FM
Bomfim
Antonio
A
Galina
Leopoldo
L
de Meis
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