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The Temperature Dependence of Protoporphyrin IX Production in Cells and Tissues
Author(s) -
Moan Johan,
Berg Kristian,
Gadmar Øystein B.,
Iani Vladimir,
Ma LiWei,
Juzenas Petras
Publication year - 1999
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1999.tb08268.x
Subject(s) - protoporphyrin ix , porphobilinogen deaminase , activation energy , chemistry , protoporphyrin , enzyme , penetration (warfare) , porphyrin , human skin , limiting , in vitro , biochemistry , mole , biophysics , photochemistry , heme , biology , organic chemistry , photodynamic therapy , mechanical engineering , operations research , engineering , genetics
Abstract The formation of protoporphyrin IX (PpIX) in human skin during topical application of 5‐aminolevulinic acid (ALA) was found to be strongly temperature dependent, with an activation energy of about 17 kcal/mol. This temperature dependence is mainly related to porphyrin production and not to ALA penetration into the skin. The penetration of ALA into mouse and human skin was almost temperature independent. The activation energy of PpIX production in mouse skin was practically identical with that in human skin. The activation energy of ALA uptake by cells in vitro was about 10 kcal/mol and that for PpIX production was about 13 kcal/mol. The latter activation energy was within the error limits similar to that for the activity of the enzyme porphobilinogen deaminase, suggesting that this enzyme might represent a rate‐limiting step for PpIX production in living tissue.