Protoporphyrin IX-induced structural and functional changes in human red blood cells, haemoglobin and myoglobin.
TL;DR: Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes, which may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms of action as therapeutic agents.
Abstract: Protoporphyrin IX and its derivatives are used as photosensitizers in the photodynamic therapy of cancer. Protoporphyrin IX penetrates into human red blood cells and releases oxygen from them. This leads to a change in the morphology of the cells. Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes. For both proteins, the binding affinity constant decreases, while the possible number of binding sites increases, as the aggregation state of the porphyrin is increased. The interactions lead to conformational changes of both haemoglobin and myoglobin as observed in circular dichroism studies. Upon binding with the proteins, protoporphyrin IX releases the heme-bound oxygen from the oxyproteins, which is dependent on the stoichiometric ratios of the porphyrin : protein. The peroxidase activities of haemoglobin and myoglobin are potentiated by the protein-porphyrin complexation. Possible mechanisms underlying the relation between the porphyrin-induced structural modifications of the heme proteins and alterations in their functional properties have been discussed. The findings may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms of action as therapeutic agents.
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TL;DR: The results suggest that drug action on hemoglobin is influenced by glycation-induced structural modification of the protein.
Abstract: Trifluoperazine (TFZ), a phenothiazine drug, penetrates into human erythrocytes and releases oxygen by interaction with hemoglobin. TFZ-induced oxygen release from hyperglycemic erythrocytes isolated from diabetic patients is considerably less compared to that from the cells of normoglycemic individuals. In diabetes mellitus, hemoglobin is significantly glycated by glucose. Non-glycated hemoglobin, HbA0 and its major glycated analog, HbA1c have been separated from the blood samples of diabetic patients. TFZ releases considerable amount of oxygen from HbA0, but very little from HbA1c. Spectrofluorimetric studies reveal that TFZ forms excited state complexes with both HbA0 and HbA1c. Titration of HbA0 with TFZ in a spectrophotometric study exhibits two isosbestic points. Similar experiment with HbA1c causes gradual loss of the Soret peak without appearance of any isosbestic point indicating a possibility of heme loss during interaction, which is also supported by gel filtration experiment and SDS-PAGE experiment followed by heme staining. The results suggest that drug action on hemoglobin is influenced by glycation-induced structural modification of the protein.
37 citations
TL;DR: Photodynamic therapy involves the systemic or topical application of a photosensitizer (PS) alongside the selective illumination of the target lesion with light of an appropriate wavelength, in order to promote localized oxidative photodamage and subsequent cell death.
Abstract: Photodynamic therapy (PDT) involves the systemic or topical application of a photosensitizer (PS), alongside the selective illumination of the target lesion with light of an appropriate wavelength, in order to promote localized oxidative photodamage and subsequent cell death. Numerous studies have demonstrated that PDT is highly effective in the destruction of fungi in vitro. The mechanism underlying the effects of PDT results from the photons of visible light of an appropriate wavelength interacting with the intracellular molecules of the PS. Reactive species are produced as a result of the oxidative stress caused by the interaction between the visible light and the biological tissue. At present, no antifungal treatment based on PDT has been licensed. However, antifungal PDT is emerging as an area of interest for research.
36 citations
TL;DR: Erythropoietic protoporphyria results from a partial deficiency of ferrochelatase and normally requires coinheritance of a common hypomorphic FECH allele in trans to a deleterious (primary) FECH mutation.
Abstract: Summary
Background Erythropoietic protoporphyria (EPP) results from a partial deficiency of ferrochelatase (FECH). Clinical expression normally requires coinheritance of a common hypomorphic FECH allele (IVS3-48C) in trans to a deleterious (primary) FECH mutation.
Objectives To characterize South African subjects with EPP, by identification and assessment of FECH sequence variations, including the IVS3-48C polymorphism.
Methods Polymerase chain reaction amplification, single-strand conformational polymorphism analysis and restriction endonuclease analysis were employed to identify and determine the frequencies of FECH sequence variations, including the IVS3-48C polymorphism, in a study cohort of symptomatic and asymptomatic South African EPP family members, and a matched control cohort.
Results We identified 29 patients from 18 families. With the exception of one family, who may represent a phenocopy of EPP, the presentation of EPP was typical. All were of European immigrant stock, and we have not identified EPP in other ethnic groups. Ten sequence variations were identified, including four apparent disease-causing mutations, the IVS3-48T/C polymorphism and five further polymorphisms. The molecular basis of EPP was established for 15 of the 17 families. A 5-bp deletion in exon 7 (757_761delAGAAG) was present in 12 of these families and haplotype studies in these families suggested a single mutational event and thus a local founder effect for this deletion. The other mutations were family specific and included two previously described splice-site mutations (IVS3+2T>G and IVS7+1G>A) and a novel 7-bp deletion in exon 4 (356_362delTTCAAGA).
Conclusions The IVS3-48C allele appears to modulate the phenotypic expression of EPP in the South African EPP cohort as observed in other populations.
35 citations
TL;DR: Molecular docking analysis confirmed results that new porphyrins and long-chain FAs compete for the common binding site FA1 in human serum albumin and meso-substituted functional groups in porphyrs play major role in the modulation of conformational rearrangements of the protein.
Abstract: Porphyrins have a unique aromatic structure determining particular photochemical properties that make them promising photosensitizers for anticancer therapy. Previously, we synthesized a set of art...
21 citations
Cites background or methods from "Protoporphyrin IX-induced structura..."
...These values are comparable to the binding constant 1.1–5.25 105M 1 determined for protoporphyrin IX–hemoglobin interactions by Sil et al. (2004)....
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...The concentration of Hb in a solution was determined from its Soret band absorbance (at 415 nm), using an extinction coefficient value of 125mM 1cm 1 (Sil et al., 2004)....
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...Standard analytical methods, such as fluorescence, UV, VIS, and NMRspectroscopy, or circular dichroism, have been used to study porphyrin binding to endogenous carrier proteins, HSA (Cohen & Margalit,1990; Karapetyan & Madakyan, 2004), and Hb (Sil et al., 2004)....
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TL;DR: E engineered porphyrin derivatives could have potential applications in energy transport and storage, supramolecular chemistry, materials science, and medicine.
Abstract: Protoporphyrin IX is a naturally occurring amphiphilic porphyrin with a rigid hydrophobic nonpolar core and two polar propionic acid substitutions on the porphyrin ring. This molecule can be modified on the hydrophilic group, which can lead to strengthened π-π-stacking and spontaneous self-assembly into novel nanostructures. Herein, we use l- phenylalanine and d-phenylalanine to modify protoporphyrin IX, and use the two derivatives for solvophobic-controlled self-assembly. Both derivatives possess two important features: 1) the aromatic core of the porphyrin for dispersive interactions and 2) a chiral amino acid to maximize the influence of chirality on selfassembly. These derivatives lead to the formation of a variety of nanostructure morphologies, such as spheres, nanofibers, lamellar structures, and thread-like and spherical shells. Solution-based self-assembly was determined by UV/Vis, fluorescence, and circular dichroism spectroscopy, and the formed nanostructures were characterized by scanning electron microscopy (SEM). Such engineered porphyrin derivatives could have potential applications in energy transport and storage, supramolecular chemistry, materials science, and medicine.
15 citations
References
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01 May 1988
TL;DR: A comprehensive review of mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed.
Abstract: Photodynamic therapy involves administration of a tumor-localizing photosensitizing agent, which may require metabolic synthesis (i.e., a prodrug), followed by activation of the agent by light of a specific wavelength. This therapy results in a sequence of photochemical and photobiologic processes that cause irreversible photodamage to tumor tissues. Results from preclinical and clinical studies conducted worldwide over a 25-year period have established photodynamic therapy as a useful treatment approach for some cancers. Since 1993, regulatory approval for photodynamic therapy involving use of a partially purified, commercially available hematoporphyrin derivative compound (Photofrin) in patients with early and advanced stage cancer of the lung, digestive tract, and genitourinary tract has been obtained in Canada, The Netherlands, France, Germany, Japan, and the United States. We have attempted to conduct and present a comprehensive review of this rapidly expanding field. Mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed. Technical issues regarding light dosimetry are also considered.
4,580 citations
1,853 citations
"Protoporphyrin IX-induced structura..." refers methods in this paper
...The αhelical contents of the protein in the presence and absence of the porphyrin were estimated from the spectra according to the relation (Chen et al 1972): Fraction of α-helix = ([θ ]222 + 2340)/– 30300, where [θ ]222 is the ellipticity at 222 nm. 2.9 Assay of peroxidase activities of Hb and…...
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TL;DR: Can the superoxide radical exert deleterious effects independent of participating with H2O2 in the production of the hydroxyl radical?
1,433 citations
"Protoporphyrin IX-induced structura..." refers background in this paper
...Superoxide radicals are generated in HRP/H2O2/NAD(P)H system (Takayama and Nakano 1977) and these radicals may inhibit the peroxidase activity of HRP (Fridovich 1986)....
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...…radicals are generated in HRP/H2O2/NAD(P)H system (Takayama and Nakano 1977) and these radicals may inhibit the peroxidase activity of HRP (Fridovich 1986). van Steveninck et al (1987, 1988) have postulated that superoxide radical generation is prevented by the porphyrin hematoporphyrin…...
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...Interaction of PP with HRP as demonstrated from this laboratory (Sil and Chakraborti 1997) may be involved in this process, because potentiation of HRP activity has a positive correlation with the extent of binding of the protein with the porphyrin....
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...Drug-protein binding; haemoglobin; myoglobin; protoporphyrin IX; red blood cells ________________ Abbreviations used: cd, Circular dichroism; EPP, erythropoietic protoporphyria; Hb, haemoglobin; HRP, horseradish peroxidase; Mb, oxymyoglobin; PDT, photodynamic therapy; PP, protoporphyrin; RBC, red blood cells; ZPP, zinc protoporphyrin....
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...It is not yet known how porphyrins remove or inhibit generation of superoxide radicals in HRP system....
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TL;DR: Studies have shown that a higher accumulation of ALA‐derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALa‐based PDT and diagnosis, however, no review updating the clinical data has appeared so far.
Abstract: BACKGROUND
Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25 years PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light Although several photosensitizers other than ALA-derived protoporphyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis However, no review updating the clinical data has appeared so far
METHODS
A review of recently published data on clinical ALA-based PDT and diagnosis was conducted
RESULTS
Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results However, the modality with present protocols does not, in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs
CONCLUSIONS
Promising results of ALA-based clinical PDT and diagnosis have been obtained The modality has advantages over conventional treatments However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue; improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems Cancer 1997; 79:2282-308 © 1997 American Cancer Society
1,000 citations