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    Biochemiluminescencja układów porfirynówych z nadtlenkiem wodoru
    (Wyższa Szkoła Rolnicza w Szczecinie, 1970) Kruk, Irena; Sławińska, Irena; Sławiński, Janusz; Wyższa Szkoła Rolnicza w Szczecinie. Katedra Fizyki; Wyższa Szkoła Rolnicza w Szczecinie. Katedra Fizyki; Wyższa Szkoła Rolnicza w Szczecinie. Katedra Fizyki
    In the present work, the current state of investigations concerning the ultra-weak chemiluminescence (CL) of animal organs, tissues, and their homogenates is discussed. This chemiluminescence is related to the non-enzymatic oxidation of biolipids; however, it may also be associated with other substrates and reactions. The authors have considered the reactions of porphyrin complexes with hydrogen peroxide as a possible source of generation of excited, light-emitting species. Currently, there is a lack of investigations addressing the CL of porphyrin complexes with H₂O₂ under uniform experimental conditions. Moreover, results from many studies are contradictory, referring exclusively to particular compounds such as catalase, peroxidase, chlorophyll, etc. The purpose of this work is to investigate the CL of different porphyrin complexes with H₂O₂ in simple systems under approximately physiological conditions. Aqueous solutions of porphyrin were injected into the H₂O₂ + NaHCO₃ - Na₂CO₃ buffer solution at pH 8.8. The solutions were vigorously mixed by a stream of O₂. Concentrations of reagents in the reaction mixture (in moles/l) were: 1 × 10⁻⁵ porphyrin or enzyme, 1 × 10⁻² buffer; temperature 303 K. Luminescence was recorded during the injection of particular components using a photoelectric system with an RCA 6655 photomultiplier. The CL kinetics of Fe³⁺, hemin, chlorophyll a, catalase, peroxidase, cytochrome c, and hemoglobin with H₂O₂, as well as the influence of respiratory and free radical inhibitors on the light reaction, were studied. Additionally, the effects of temperature, pH, and ultraviolet irradiation on fresh blood and hemoglobin solution were tested. It was found that the CL kinetics consists of two steps: (1) a high peak with a duration of 10–15 seconds, and (2) a long-lived but low-intensity luminescence. Both steps follow first-order kinetics with rate constants k₁ = 0.18–0.03 s⁻¹ and k₂ = (2.8–3.6) × 10⁻² s⁻¹, respectively. Respiratory inhibitors such as KCN, NaN₃, NaF, as well as thermal and hydrolytic inactivation of Fe-porphyrin-proteides, strongly affect the maximal intensity (Iₘₐₓ) and total light output (J) of CL. Free radical inhibitors such as ascorbic acid, α-naphthol, and hydroquinone quench 80–100% of Iₘₐₓ and J of CL. An increase in pH and temperature results in elevation of Iₘₐₓ and J. The temperature coefficient for CL of the hemoglobin-H₂O₂-buffer system is 1.55 ± 0.3, and the activation energy is 22.76 ± 2.15 kJ/mole in the range of 298–313 K. The solution of fresh blood and hemoglobin irradiated with UV (350 W, 2–15 minutes) exhibits CL similar to that with H₂O₂ buffer but with 10–15 times lower intensity. Data indicate that an important role in generating the excited, light-emitting species is played by the nucleophilic reaction of the ·OOH radical ion with the carbon atom in the methine bridge, which possesses the smallest electron density (q = 0.954), and, on the other hand, the presence of coordinatively bound Fe in the porphyrin ring.