Porphyrin-sensitized photooxidation of horseradish apoperoxidase

Journal Article · Wed Dec 31 23:00:00 EST 1975 · Arch. Biochem. Biophys.; (United States)

OSTI ID:7332173

Kang, Y J; Spikes, J D

Horseradish apoperoxidase (apoHRP) was reconstituted with various porphyrin derivatives, e.g., ferric, cupric, manganese, and zinc protoporphyrin IX, metal-free protoporphyrin IX, hematoporphyrin IX and deuteroporphyrin IX. The visible absorption spectra of these porphyrin-apoHRP complexes were examined. The time required for maximum development of the new Soret peak after reconstitution was used to measure the rate of porphyrin-apoHRP reconstitution. All of the four metal-protoporphyrins reconstituted with apoHRP at the same rate as metal-free protoporphyrin IX, whereas, for the metal-free porphyrins, the rates of reconstitution were in the order of deuteroporphyrin IX > hematoporphyrin IX > protoporphyrin IX. The porphyrins on the reconstituted porphyrin-apoHRP complexes were used as localized photosensitizers for photodynamic studies. No amino acid residues were oxidized on illumination of the ferric, cupric and manganese protoporphyrin IX-apoHRP complexes due to the paramagnetic properties of these metal ions. With diamagnetic zinc ion, two histidine and one methionine residues were oxidized, which was the same as in the protoporphyrin IX- and hematoporphyrin IX-apoHRP complexes. However, only one histidine was destroyed on illumination of the deuteroporphyrin IX-apoHRP complex. The results confirmed the resistance of horseradish peroxidase to photodynamic action and suggested the involvement of at least one histidine residue in the heme environment of horseradish peroxidase.

• Research Organization: Univ. of Utah, Salt Lake City
• OSTI ID: 7332173
• Journal Information: Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 172; ISSN ABBIA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AZOLES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
OXIDOREDUCTASES
PEROXIDASES
PORPHYRINS
RADIATIONS
VISIBLE RADIATION