1
|
Zhao X, Cheng H, Wang Q, Nie W, Yang Y, Yang X, Zhang K, Shi J, Liu J. Regulating Photosensitizer Metabolism with DNAzyme-Loaded Nanoparticles for Amplified Mitochondria-Targeting Photodynamic Immunotherapy. ACS NANO 2023; 17:13746-13759. [PMID: 37438324 DOI: 10.1021/acsnano.3c03308] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Mitochondria-specific photosensitizer accumulation is highly recommended for photodynamic therapy and mitochondrial DNA (mtDNA) oxidative damage-based innate immunotherapy but remains challenging. 5-Aminolevulinic acid (ALA), precursor of photosensitizer protoporphyrin IX (PpIX), can induce the exclusive biosynthesis of PpIX in mitochondria. Nevertheless, its photodynamic effect is limited by the intracellular biotransformation of ALA in tumors. Here, we report a photosensitizer metabolism-regulating strategy using ALA/DNAzyme-co-loaded nanoparticles (ALA&Dz@ZIF-PEG) for mitochondria-targeting photodynamic immunotherapy. The zeolitic imidazolate framework (ZIF-8) nanoparticles can be disassembled and release large amounts of zinc ions (Zn2+) within tumor cells. Notably, Zn2+ can relieve tumor hypoxia for promoting the conversion of ALA to PpIX. Moreover, Zn2+ acts as a cofactor of rationally designed DNAzyme for silencing excessive ferrochelatase (FECH; which catalyzes PpIX into photoinactive Heme), cooperatively promoting the exclusive accumulation of PpIX in mitochondria via the "open source and reduced expenditure" manner. Subsequently, the photodynamic effects derived from PpIX lead to the damage and release of mtDNA and activate the innate immune response. In addition, the released Zn2+ further enhances the mtDNA/cGAS-STING pathway mediated innate immunity. The ALA&Dz@ZIF-PEG system induced 3 times more PpIX accumulation than ALA-loaded liposome, significantly enhancing tumor regression in xenograft tumor models.
Collapse
Affiliation(s)
- Xiu Zhao
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Hui Cheng
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Qiongwei Wang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Weimin Nie
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Yue Yang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Xinyuan Yang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
| | - Kaixiang Zhang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Zhengzhou 450001, People's Republic of China
| | - Jinjin Shi
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Zhengzhou 450001, People's Republic of China
| | - Junjie Liu
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou 450001, People's Republic of China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou 450001, People's Republic of China
- Collaborative Innovation Center of New Drug Research and Safety Evaluation, Zhengzhou 450001, People's Republic of China
| |
Collapse
|
2
|
Di Pierro E, De Canio M, Mercadante R, Savino M, Granata F, Tavazzi D, Nicolli AM, Trevisan A, Marchini S, Fustinoni S. Laboratory Diagnosis of Porphyria. Diagnostics (Basel) 2021; 11:diagnostics11081343. [PMID: 34441276 PMCID: PMC8391404 DOI: 10.3390/diagnostics11081343] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/13/2021] [Accepted: 07/22/2021] [Indexed: 12/13/2022] Open
Abstract
Porphyrias are a group of diseases that are clinically and genetically heterogeneous and originate mostly from inherited dysfunctions of specific enzymes involved in heme biosynthesis. Such dysfunctions result in the excessive production and excretion of the intermediates of the heme biosynthesis pathway in the blood, urine, or feces, and these intermediates are responsible for specific clinical presentations. Porphyrias continue to be underdiagnosed, although laboratory diagnosis based on the measurement of metabolites could be utilized to support clinical suspicion in all symptomatic patients. Moreover, the measurement of enzymatic activities along with a molecular analysis may confirm the diagnosis and are, therefore, crucial for identifying pre-symptomatic carriers. The present review provides an overview of the laboratory assays used most commonly for establishing the diagnosis of porphyria. This would assist the clinicians in prescribing appropriate diagnostic testing and interpreting the testing results.
Collapse
Affiliation(s)
- Elena Di Pierro
- Dipartimento di Medicina Interna, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy;
- Correspondence: ; Tel.: +39-0255036155
| | - Michele De Canio
- Porphyria and Rare Diseases Centre, San Gallicano Dermatological Institute IRCCS, 00144 Rome, Italy;
| | - Rosa Mercadante
- EPIGET-Epidemiology, Epigenetics, and Toxicology Lab, Department of Clinical Sciences and Community Health, University of Milan, 20122 Milan, Italy; (R.M.); (D.T.); (S.F.)
| | - Maria Savino
- Servizio di Medicina Trasfusionale e Laboratorio Analisi, Laboratorio di Immunogenetica, IRCCS Ospedale “Casa Sollievo della Sofferenza”, 71013 San Giovanni Rotondo, Italy;
| | - Francesca Granata
- Dipartimento di Medicina Interna, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy;
| | - Dario Tavazzi
- EPIGET-Epidemiology, Epigenetics, and Toxicology Lab, Department of Clinical Sciences and Community Health, University of Milan, 20122 Milan, Italy; (R.M.); (D.T.); (S.F.)
| | - Anna Maria Nicolli
- Dipartimento di Scienze Cardio-Toraco-Vascolari e Sanità Pubblica, Università Degli Studi di Padova, 35121 Padova, Italy; (A.M.N.); (A.T.)
| | - Andrea Trevisan
- Dipartimento di Scienze Cardio-Toraco-Vascolari e Sanità Pubblica, Università Degli Studi di Padova, 35121 Padova, Italy; (A.M.N.); (A.T.)
| | - Stefano Marchini
- Laboratorio Malattie Rare-Settore Porfirie, Dipartimento di Scienze Mediche, Chirurgiche, Materno-Infantili e Dell’Adulto, Azienda Ospedaliero-Universitaria Policlinico di Modena, 41125 Modena, Italy;
| | - Silvia Fustinoni
- EPIGET-Epidemiology, Epigenetics, and Toxicology Lab, Department of Clinical Sciences and Community Health, University of Milan, 20122 Milan, Italy; (R.M.); (D.T.); (S.F.)
- Environmental and Industrial Toxicology Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy
| |
Collapse
|
3
|
Sigala PA, Crowley JR, Henderson JP, Goldberg DE. Deconvoluting heme biosynthesis to target blood-stage malaria parasites. eLife 2015; 4. [PMID: 26173178 PMCID: PMC4532139 DOI: 10.7554/elife.09143] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/13/2015] [Indexed: 12/03/2022] Open
Abstract
Heme metabolism is central to blood-stage infection by the malaria parasite Plasmodium falciparum. Parasites retain a heme biosynthesis pathway but do not require its activity during infection of heme-rich erythrocytes, where they can scavenge host heme to meet metabolic needs. Nevertheless, heme biosynthesis in parasite-infected erythrocytes can be potently stimulated by exogenous 5-aminolevulinic acid (ALA), resulting in accumulation of the phototoxic intermediate protoporphyrin IX (PPIX). Here we use photodynamic imaging, mass spectrometry, parasite gene disruption, and chemical probes to reveal that vestigial host enzymes in the cytoplasm of Plasmodium-infected erythrocytes contribute to ALA-stimulated heme biosynthesis and that ALA uptake depends on parasite-established permeability pathways. We show that PPIX accumulation in infected erythrocytes can be harnessed for antimalarial chemotherapy using luminol-based chemiluminescence and combinatorial stimulation by low-dose artemisinin to photoactivate PPIX to produce cytotoxic reactive oxygen. This photodynamic strategy has the advantage of exploiting host enzymes refractory to resistance-conferring mutations. DOI:http://dx.doi.org/10.7554/eLife.09143.001 Malaria is a devastating infectious disease that is caused by single-celled parasites called Plasmodium that can live inside red blood cells. Several important proteins from these parasites require a small molecule called heme in order to work. The parasites have enzymes that make heme via a series of intermediate steps. However, it remains unclear exactly how important this ‘pathway’ of enzymes is for the parasite, and whether this pathway could be targeted by drugs to treat malaria. Now Sigala et al. have used a range of genetic and biochemical approaches to better understand the production of heme molecules in Plasmodium-infected red blood cells. First, several parasite genes that encode the enzymes used to make heme molecules were deleted. Unexpectedly, these gene deletions did not affect the ability of the infected blood cells to make heme. This result suggested that the parasites do not use their own pathway to produce heme while they are growing in the bloodstream. Sigala et al. then showed that human enzymes involved in making heme, most of which are also found within the infected red blood cells, are still active. These human enzymes provide a parallel pathway that can link up with the final parasite enzyme to generate heme. Further experiments revealed that the activity of the human enzymes could be strongly stimulated by providing the pathway with one of the building blocks used to make heme. This stimulation led to the build-up of an intermediate molecule called PPIX. This intermediate molecule can kill cells when it is exposed to light—a property that is called ‘phototoxicity’. Sigala et al. showed that treating infected red blood cells with a new combination of non-toxic chemicals that emit light can activate PPIX in the bloodstream and can selectively kill the malaria parasites while leaving uninfected cells intact. These findings suggest a new treatment that could be effective against blood-stage malaria. Furthermore, the parasite will be unable to easily mutate to avoid the effects of this treatment because it relies on human proteins that are already made. Future work is now needed to optimize the dosage and the combination of drugs that could provide such a treatment. DOI:http://dx.doi.org/10.7554/eLife.09143.002
Collapse
Affiliation(s)
- Paul A Sigala
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, United States
| | - Jan R Crowley
- Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, United States
| | - Jeffrey P Henderson
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, United States
| | - Daniel E Goldberg
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, United States
| |
Collapse
|
4
|
Sullivan SA, Streit BR, Ferguson EL, Jean PA, McNett DA, Llames LT, DuBois JL. Mass-spectrometric profiling of porphyrins in complex biological samples with fundamental, toxicological, and pharmacological applications. Anal Biochem 2015; 478:82-9. [PMID: 25769421 DOI: 10.1016/j.ab.2015.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/19/2015] [Accepted: 03/03/2015] [Indexed: 10/23/2022]
Abstract
Rapid, high-throughput, and quantitative evaluations of biological metabolites in complex milieu are increasingly required for biochemical, toxicological, pharmacological, and environmental analyses. They are also essential for the development, testing, and improvement of new commercial chemical products. We demonstrate the application of ultra-high performance liquid chromatography-mass spectrometry (uHPLC-MS), employing an electrospray ionization source and a high accuracy quadrupole time-of-flight mass analyzer, for the identification and quantification of a series of porphyrin derivatives in liver: a matrix of particular relevance in toxicological or pharmacological testing. Exact mass is used to identify and quantify the metabolites. Chromatography enhances sensitivity and alleviates potential saturation issues by fanning out the contents of a complex sample before their injection into the spectrometer, but is not strictly necessary for the analysis. Extraction and sample treatment procedures are evaluated and matrix effects discussed. Using this method, the known mechanism of action of a well-characterized porphyrinogenic agent was verified in liver extracts from treated rats. The method was also validated for use with bacterial cells. This exact-mass method uses workhorse instruments available in many laboratories, providing a highly flexible alternative to existing HPLC- and MS/MS-based approaches for the simultaneous analysis of multiple compounds in biological media.
Collapse
Affiliation(s)
- Sarah A Sullivan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Bennett R Streit
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59713, USA
| | - Ethan L Ferguson
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Paul A Jean
- Health and Environmental Sciences, Dow Corning Corporation, Auburn, MI 48611, USA
| | - Debra A McNett
- Health and Environmental Sciences, Dow Corning Corporation, Auburn, MI 48611, USA
| | - Louis T Llames
- Health and Environmental Sciences, Dow Corning Corporation, Auburn, MI 48611, USA.
| | - Jennifer L DuBois
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59713, USA.
| |
Collapse
|
5
|
Kim EJ, Oh EK, Lee JK. Role of HemF and HemN in the heme biosynthesis of Vibrio vulnificus under S-adenosylmethionine-limiting conditions. Mol Microbiol 2015; 96:497-512. [PMID: 25626927 DOI: 10.1111/mmi.12951] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2015] [Indexed: 11/25/2022]
Abstract
Vibrio vulnificus contains two coproporphyrinogen III oxidases (CPOs): O2-dependent HemF and O2-independent HemN. The growth of the hemF mutant HF1 was similar to wild-type cells at pH 7.5 under 2% O2 conditions where HemN was active and had a half-life of 64 min. However, HF1 did not grow when the medium pH decreased to pH 5.0, where oxidative stress affects endogenous S-adenosylmethionine (SAM) levels. The growth of HF1 was restored not only by elevating the expression of MnSOD but also through the exogenous addition of SAM. For HF1 to grow under these SAM-limiting conditions, a mutation arose in hemN, encoding HemNY74F . Refolding of the denatured enzymes in vitro revealed that the apparent binding affinity of HemNY74F for the cofactor SAM1, which coordinates the 4Fe-4S cluster, was approximately sixfold higher than that of HemN. The Km of HemNY74F for the co-substrate SAM2, which provides radicals for CPO reactions, was threefold lower than that of HemN. Thus, affinities for both SAM1 and SAM2 were higher with the Y74F mutation. Taken together, when SAM is limiting, HemN is apparently nonfunctional, and heme synthesis is continued by HemF.
Collapse
Affiliation(s)
- Eui-Jin Kim
- Department of Life Science, Sogang University, Seoul, 121-742, Korea
| | | | | |
Collapse
|
6
|
Ke H, Sigala PA, Miura K, Morrisey JM, Mather MW, Crowley JR, Henderson JP, Goldberg DE, Long CA, Vaidya AB. The heme biosynthesis pathway is essential for Plasmodium falciparum development in mosquito stage but not in blood stages. J Biol Chem 2014; 289:34827-37. [PMID: 25352601 DOI: 10.1074/jbc.m114.615831] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Heme is an essential cofactor for aerobic organisms. Its redox chemistry is central to a variety of biological functions mediated by hemoproteins. In blood stages, malaria parasites consume most of the hemoglobin inside the infected erythrocytes, forming nontoxic hemozoin crystals from large quantities of heme released during digestion. At the same time, the parasites possess a heme de novo biosynthetic pathway. This pathway in the human malaria parasite Plasmodium falciparum has been considered essential and is proposed as a potential drug target. However, we successfully disrupted the first and last genes of the pathway, individually and in combination. These knock-out parasite lines, lacking 5-aminolevulinic acid synthase and/or ferrochelatase (FC), grew normally in blood-stage culture and exhibited no changes in sensitivity to heme-related antimalarial drugs. We developed a sensitive LC-MS/MS assay to monitor stable isotope incorporation into heme from its precursor 5-[(13)C4]aminolevulinic acid, and this assay confirmed that de novo heme synthesis was ablated in FC knock-out parasites. Disrupting the FC gene also caused no defects in gametocyte generation or maturation but resulted in a greater than 70% reduction in male gamete formation and completely prevented oocyst formation in female Anopheles stephensi mosquitoes. Our data demonstrate that the heme biosynthesis pathway is not essential for asexual blood-stage growth of P. falciparum parasites but is required for mosquito transmission. Drug inhibition of pathway activity is therefore unlikely to provide successful antimalarial therapy. These data also suggest the existence of a parasite mechanism for scavenging host heme to meet metabolic needs.
Collapse
Affiliation(s)
- Hangjun Ke
- From the Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Paul A Sigala
- the Department of Molecular Microbiology and the Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Kazutoyo Miura
- the Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Rockville, Maryland 20852, and
| | - Joanne M Morrisey
- From the Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Michael W Mather
- From the Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Jan R Crowley
- the Center for Women's Infectious Disease Research and
| | - Jeffrey P Henderson
- the Center for Women's Infectious Disease Research and Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Daniel E Goldberg
- the Department of Molecular Microbiology and the Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Carole A Long
- the Laboratory of Malaria and Vector Research, NIAID, National Institutes of Health, Rockville, Maryland 20852, and
| | - Akhil B Vaidya
- From the Center for Molecular Parasitology, Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129,
| |
Collapse
|
7
|
Benton CM, Lim CK. Liquid chromatography and mass spectrometry of haem biosynthetic intermediates: a review. Biomed Chromatogr 2012; 26:1009-23. [DOI: 10.1002/bmc.2772] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
| | - Chang Kee Lim
- Clinical Biochemistry; King's College Hospital; Denmark Hill; London; SE5 9RS; UK
| |
Collapse
|
8
|
Lu X, Zhao D, Song Z, Wu B, Lu B, Zhou X, Xue Z. A valuable visual colorimetric and electrochemical biosensor for porphyrin. Biosens Bioelectron 2011; 27:172-7. [DOI: 10.1016/j.bios.2011.06.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/27/2011] [Accepted: 06/28/2011] [Indexed: 10/18/2022]
|
9
|
Choiniere JR, Scott CR, Gelb MH, Turecek F. Direct assay of delta-aminolevulinic acid dehydratase in heme biosynthesis for the detection of porphyrias by tandem mass spectrometry. Anal Chem 2010; 82:6730-6. [PMID: 20583792 DOI: 10.1021/ac101111m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report a new assay of human delta-aminolevulinic acid dehydratase (ALAD), an enzyme converting delta-aminolevulinic acid (ALA) into porphobilinogen. The assay is developed for use in the clinical diagnosis of delta-aminolevulinic acid dehydratase-deficient porphyria, a rare enzymatic deficiency of the heme biosynthetic pathway. The assay involves the incubation of erythrocyte lysate with the natural substrate, ALA, followed by quantitative in situ conversion of porphobilinogen to its butyramide, and liquid-liquid extraction into a mass spectrometer-friendly solvent. Quantitation of the butyrylated porphobilinogen is done by electrospray ionization tandem mass spectrometry, using a deuterium labeled internal standard. The assay stays well within the range wherein ALAD activity is linear with time. The K(m) of ALAD for ALA was measured as 333 microM, and the V(max) was 19.3 microM/h. Average enzyme activity among a random sample of 36 anonymous individuals was 277 micromol/L erythrocyte lysate/hour with a standard deviation of 90 micromol/L erythrocyte lysate/hour. The tandem mass spectrometric assay should easily detect the enzyme deficiency, which causes a reduction of activity by 95-99%. The assay shows good reproducibility and low background, requires a simple workup, and uses a commercially available substrate.
Collapse
Affiliation(s)
- John R Choiniere
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | | | | | | |
Collapse
|
10
|
Wang Y, Scott CR, Gelb MH, Turecek F. Direct assay of enzymes in heme biosynthesis for the detection of porphyrias by tandem mass spectrometry. Porphobilinogen deaminase. Anal Chem 2008; 80:2606-11. [PMID: 18294005 DOI: 10.1021/ac702244x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a new assay of human porphobilinogen deaminase (PBGD). Deficiency in this enzyme activity causes acute intermittent porphyria, the most common disorder of heme biosynthesis. The assay involves incubation of blood erythrocyte lysate with porphobilinogen, the natural PBGD substrate. Two subsequent enzymes in the heme biosynthetic pathway, uroporphyrinogen III synthase and uroporphyrinogen decarboxylase, are deactivated by heating so that their activity does not interfere with the PBGD assay. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) is used to monitor the production of uroporphyrinogen I and thus measure the PGBD activity. A simple and efficient workup using liquid-liquid extraction with >90% product recovery was employed to avoid separation by liquid chromatography. The assays show good reproducibility (+/-3.3%) and linear dependence of the uroporphyrinogen I formation on incubation time and protein amount. The Km of PGBD for porphobilinogen was measured as 11.2 +/- 0.5 microM with Vmax of 0.0041 +/- 0.0002 microM/(min.mg of hemoglobin). The coefficient of variation of PBGD activity among several unaffected individuals (12%) is significantly lower than the decrease due to acute intermittent porphyria (50%).
Collapse
Affiliation(s)
- Yuesong Wang
- Departments of Chemistry, Pediatrics, and Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | | | | | | |
Collapse
|