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Journal ArticleDOI

Protoporphyrin IX-induced structural and functional changes in human red blood cells, haemoglobin and myoglobin.

01 Sep 2004-Journal of Biosciences (J Biosci)-Vol. 29, Iss: 3, pp 281-291
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.
Citations
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Journal ArticleDOI
01 Dec 2009-Optik
TL;DR: In this article, the cell proliferation process in chick embryos was monitored using fluorometry and the 410nm-excited emission spectra of albumin from controlled and incubated eggs were measured.

1 citations

Journal Article
TL;DR: PEGylated silver nanoparticles lead to secondary structural changes and hemoglobin unfolding, which may cause the molecular toxicity of proteins, and it is suggested that by changing the coating, size, or shape of nanoparticles and optimizing them, the possible side effects of nanoparticle on the structure and function of the protein can be prevented.
Abstract: *Correspondinauthor:Samane Zolghadri Jahromi Email: Z.jahromi@ut.ac.ir Background: The material is always covered by proteins immediately upon contact with a physiological environment. Hemoglobin (Hb) is one of the major blood proteins. Due to the entry of substances into blood, hemoglobin may interact with them. The interaction between Hemoglobin and ligands such as nanoparticles is very important and may cause structural and functional changes on Hemoglobin. According to the recent studies, PEG (poly ethylene glycol) coated nanoparticles have better biocompatibility compared with noncoated nanoparticles, thus the present study was conducted to investigate the interaction of PEG-silver nanoparticles with hemoglobin. Materials and Methods: In the present experimental study, various spectroscopic methods, including UV Visible, fluorescence, and Circular Dichroism (CD), were used to evaluate the interaction of silver nanoparticles with polyethylene glycol coating and hemoglobin. Using these methods, the effects of nanoparticles on the second structure and variations in the alpha helix and beta sheets of the protein, as well as changes in the third structure, and thus the change in the protein function, were investigated. Results: The results of fluorescence spectroscopy and UV/Vis absorption spectroscopy indicated that the structure of the Trp residue environments was altered and the physiological functions of Hb were affected by silver nanoparticles coated with poly ethylene glycol. It could also be suggested that due to the binding of silver nanoparticle to Hb, some conformational changes are induced, enhancing the hydrophobicity. These nanoparticles have increased the ratio of deoxy and decreased hemoglobin tendency to oxygen. This increase in the highest concentration of nanoparticles is six times as common. Conclusion: The results showed that PEGylated silver nanoparticles lead to secondary structural changes and hemoglobin unfolding. Therefore, PEGylated silver nanoparticles decrease the hemoglobin function by decreasing the hemoglobin tendency toward oxygen. As a result, silver nanoparticles may cause the molecular toxicity of proteins. Considering the results obtained and the importance of nanoparticles biosafety, it is suggested that by changing the coating, size, or shape of nanoparticles and optimizing them, the possible side effects of nanoparticles on the structure and function of the protein can be prevented.

1 citations

19 Mar 2010
TL;DR: In this paper, the binding constants of porphyrins with various types of proteins and their localization on the protein globule were determined using absorption and fluorescence spectroscopy.
Abstract: It is shown, that the methods of absorption and fluorescence spectroscopy allow determining the binding constants of porphyrins with various types of serum albumin (SA) and their localization on the protein globule correctly enough. Researches testify about good binding of porphyrins with protein at low ionic strength of solution whereas at 0,1 M buffer solution the interaction of bovine serum albumin with porphyrins is considerably weak. Values of binding constants of cationic porphyrins prove their sorption not only on the surface of proteins but also in the globule of SA, which is confirmed also by computer simulation of SA-porphyrin interaction. Ցույց է տրված, որ կլանման և ֆլուորեսցենտային սպեկտրասկոպիայի մեթոդները թույլ են տալիս բավականին ճշգրիտ որոշել պորֆիրինների կապման հաստատունները շիճուկային ալբումինի (ՇԱ) տարբեր տեսակների հետ և նրանց տեղայնացումը սպիտակուցի վրա: Հետազոտությունները վկայում են որ ցածր իոնային ուժի դեպքում պորֆիրինները լավ են կապվում սպիտակուցի հետ, մինչդեռ 0,1 M բուֆերի լուծույթում ցուլի շիճուկային ալբումինի համագործակցությունը պորֆիրինների հետ զգալիորեն թույլ է: Կատիոնային պորֆիրինների կապման հաստատունների մեծությունները վկայում են նրանց սորբցիայի մասին սպիտակուցի ինչպես մակերևույթի վրա, այնպես էլ գլոբուլի մեջ, ինչը նույնպես հաստատվում է համակարգչային մոդելավորումով ՇԱ-պորֆիրին փոխազդեցության ուսումնասիրությամբ: Показано, что методы абсорбционной и флуоресцентной спектроскопии позволяют достаточно корректно определять константы связывания порфиринов с различными типами сывороточного альбумина (СА) и их локализацию на белковой глобуле. Исследования свидетельствуют о хорошем связывании порфиринов с белком при низкой ионной силе, тогда как в 0,1 М растворе буфера взаимодействие бычьего сывороточного альбумина с порфиринами значительно слабее. Константы связывания катионных порфиринов свидетельствуют об их сорбции как на поверхности белка, так и внутри глобулы СА, что подтверждается также компьютерным моделированием взаимодействия СА - порфирин.

1 citations


Cites background from "Protoporphyrin IX-induced structura..."

  • ...On the organism level the PS transport to tumors is done by blood carrier proteins such as serum albumin (SA) [5, 22], low and high density lipoproteins [14], and hemoglobin [23]....

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Proceedings ArticleDOI
TL;DR: To identify if metHb can be formed in vitro as a result of oxidative stress caused by singlet oxygen and ROS produced during PDT, the methemoglobin absorbance spectrum was studied, and found to be strongly dependant on pH.
Abstract: Photodynamic therapy (PDT) is a treatment modality which has been shown to be effective for both malignant and non-malignant diseases. New photosensitizers such as hexyl-aminolevulinate (HAL) may increase the efficiency of PDT. HAL penetrates into the cell where the photosensitizer protoporphyrin IX (PPIX) is produced endogenously. In a previous study on HAL based PDT treatment of rat bladder cancer (AY-27 transitional cell carcinoma), a depression of the optical reflectance spectra after treatment was observed in some of the animals. This depression of the spectra was caused by metHemoglobin (metHb). MetHb is an indication of oxidative stress, and can be formed as a result of for instance UV-radiation and heating of blood. The aim of this study was to identify if metHb can be formed in vitro as a result of oxidative stress caused by singlet oxygen and ROS produced during PDT. Methemoglobin formed during PDT might thus be used as an indirect measure of the photochemical processes. This may help predict the PDT treatment outcome. Red blood cells mixed with AY-27 cells exposed to HAL, or PPIX received light treatment, and the changes in the absorption spectra were measured spectrophotometrically. The methemoglobin absorbance spectrum was also studied, and found to be strongly dependant on pH. Hemolysis of erythrocytes by PDT was found, however no metHb was formed in vitro.

1 citations

References
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Book
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

Journal ArticleDOI

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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01 Jan 1975

1,757 citations

Journal ArticleDOI
Irwin Fridovich1
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)....

    [...]

  • ...…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....

    [...]

  • ...It is not yet known how porphyrins remove or inhibit generation of superoxide radicals in HRP system....

    [...]

Journal ArticleDOI
15 Jun 1997-Cancer
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