Biomedical subjects

Jerzy Jankun

Publications and source records attributed to Jerzy Jankun.

17 recordsLinked to original sources

PubMed2006

Vascular endothelial growth factor production in human prostate cancer cells is stimulated by overexpression of platelet 12-lipoxygenase.

BACKGROUND: Elevated platelet 12-Lipoxygenase (P12-LOX) expression is associated with advanced stage and grade prostate cancer and overexpression in PC-3 cells promotes tumor growth and angiogenesis. The mechanisms underlying the role of P12-LOX in angiogenesis remain unclear. METHODS: Enzyme linked immunosorbent assays were used to measure 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) and vascular endothelial growth factor (VEGF) in conditioned media of PC-3 cells stably overexpressing human P12-LOX. Immunoblotting was used to observe stimulation of signal transduction in prostate cancer cell lines following exposure to 12(S)-HETE. RESULTS: P12-LOX overexpression promotes increased accumulation of 12(S)-HETE and VEGF in culture media leading to constitutive ERK1/2 phosphorylation. 12(S)-HETE stimulates ERK1/2 phosphorylation via a pertussis toxin sensitive G-protein coupled receptor (GPCR) and MEK; the inhibition of which reduces VEGF accumulation by 36% and 70%, respectively. CONCLUSIONS: Our data provide insight into a possible mechanism by which prostate cancer cells with elevated expression of P12-LOX stimulate VEGF production, thus increasing their angiogenic potential.

Arachidonate 12-Lipoxygenase↗

PubMed2006

Synthetic curcuminoids modulate the arachidonic acid metabolism of human platelet 12-lipoxygenase and reduce sprout formation of human endothelial cells.

Platelet 12-lipoxygenase (P-12-LOX) is overexpressed in different types of cancers, including prostate cancer, and the level of expression is correlated with the grade of this cancer. Arachidonic acid is metabolized by 12-LOX to 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE], and this biologically active metabolite is involved in prostate cancer progression by modulating cell proliferation in multiple cancer-related pathways inducing angiogenesis and metastasis. Thus, inhibition of P-12-LOX can reduce these two processes. Several lipoxygenase inhibitors are known, including plant and mammalian lipoxygenases, but only a few of them are known inhibitors of P-12-LOX. Curcumin is one of these lipoxygenase inhibitors. Using a homology model of the three-dimensional structure of human P-12-LOX, we did computational docking of synthetic curcuminoids (curcumin derivatives) to identify inhibitors superior to curcumin. Docking of the known inhibitors curcumin and NDGA to P-12-LOX was used to optimize the docking protocol for the system in study. Over 75% of the compounds of interest were successfully docked into the active site of P-12-LOX, many of them sharing similar binding modes. Curcuminoids that did not dock into the active site did not inhibit P-12-LOX. From a set of the curcuminoids that were successfully docked and selected for testing, two were found to inhibit human lipoxygenase better than curcumin. False-positive curcuminoids showed high LogP (theoretical) values, indicating poor water solubility, a possible reason for lack of inhibitory activity or/and nonrealistic binding. Additionally, the curcuminoids inhibiting P-12-LOX were tested for their ability to reduce sprout formation of endothelial cells (in vitro model of angiogenesis). We found that only curcuminoids inhibiting human P-12-LOX and the known inhibitor NDGA reduced sprout formation. Only limited inhibition of sprout formation at approximately IC(50) concentrations has been seen. At IC(50), a substantial amount of 12-HETE can be produced by lipoxygenase, providing a stimulus for angiogenic sprouting of endothelial cells. Increasing the concentration of lipoxygenase inhibitors above IC(50), thus decreasing the concentration of 12(S)-HETE produced, greatly reduced sprout formation for all inhibitors tested. This universal event for all tested lipoxygenase inhibitors suggests that the inhibition of sprout formation was most likely due to the inhibition of human P-12-LOX but not other cancer-related pathways.

Amino Acid Sequence↗

PubMed2006

Plasminogen activator inhibitor-1 is locked in active conformation and polymerizes upon binding ligands neutralizing its activity.

Plasminogen activator inhibitor-1 (PAI-1), a member of the serpin super-family, forms a covalent complex with its target proteinases, such as tissue and urokinase plasminogen activators. Thus, PAI-1 controls the physiological and pathological proteolysis. An abnormal expression of PAI-1 has been observed in different diseases, which can be treated by returning the proteolysis back to normal physiological levels. It has been reported that some PAI-1 inhibitors neutralize its activity by accelerating the conversion of PAI-1 into a latent form. We have found small organic chemicals that also neutralize PAI-1 activity, but by a different mechanism. Using the NBD fluorescent probe [N,N'-dimethyl-N-(acetyl)-N'-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)] incorporated into the reactive center loop (RCL) of PAI-1, we measured the kinetics of conversion from an active to a latent form. Unexpectedly, we found that some inhibitors of PAI-1 arrest this serpin in its active form instead of increasing the speed of conversion. Using docking calculations, we located two possible binding sites for these chemicals. The sites are in proximity of the P1/P1' amino acids of the RCL of PAI-1. Binding in this area can inactivate PAI-1 and additionally create a steric obstacle on the RCL making insertion of this loop between the A3 and A5 strands more difficult; hence abolishing a necessary step in the conversion of this protein into the latent form. Additionally, PAI-1 inhibitors link the RCL of one PAI-1 molecule with the strand 3C and strand 4C or helix A and strand 1B regions of the other PAI-1 molecule aiding polymerization or stabilizing the junction of the two. The polymerization of PAI-1 reduces PAI-1 activity by encapsulating the critical RCL fragment inside the formed PAI-1/PAI-1 polymers.

Amino Acid Sequence↗

PubMed2006

Nutraceutical inhibitors of urokinase: potential applications in prostate cancer prevention and treatment.

Epidemiological studies have shown that the clinical incidence of prostate cancer varies by geographical area. When individuals move from low to high prostate cancer incidence areas, the risk of developing cancer increases to the level observed in the indigenous population. It was hypothesized that this observation is related to diet or more specifically to nutraceuticals present in food, medicinal plants, and herbs. Nutraceuticals can inhibit or downregulate enzymes critical for cancer formation. We tested this hypothesis by searching the 3D database of nutraceuticals and docking them to the 3D structure of urokinase. In addition to nutraceuticals, the data-base contains known uPA inhibitors that served as positive controls. From >1,000 compounds, several potential uPA inhibitors have been selected (antipain, leupeptin, folic acid, rosmarinic acid, lavendustin A, fisetin, myricetin, tolfenamic acid). Some of these were subject to further tests on inhibitory activity and inhibition of sprout formation. We found that compounds selected by computational methods indeed inhibit uPA and sprout formation. However, because the database of nutraceuticals was small, we did not expect to find either many or high affinity/specific inhibitors. Rather, we tested this method as a proof of concept. All the facts described above support the hypothesis that nutrients selected by computerized searches can inhibit unwanted uPA activity and thus reduce angiogenesis. If true, a proper diet rich in uPA-inhibiting nutraceuticals might support the prevention of prostrate cancer and be a supportive tool in prostate cancer treatment.

Cells, Cultured↗

PubMed2005

Diverse optical characteristic of the prostate and light delivery system: implications for computer modelling of prostatic photodynamic therapy.

OBJECTIVE: To explore the use of photodynamic therapy (PDT) as a minimally invasive form of treatment for organ-confined prostate cancer, for although there are several therapies, ablative treatments are associated with significant morbidity. MATERIALS AND METHODS: Using the photosensitizer tin etiopurpurin, dogs were treated with interstitially placed laser fibres in an effort to validate PDT for treating prostate cancer. Earlier models assumed a uniform distribution of light output from a cylindrical fibre and a uniform attenuation coefficient throughout the prostate. Subsequent observations show that this model was too simple and that light radiance is not linear. To overcome under-treatment, a computer program to complement real-time fibre placement was developed. RESULTS: As light radiance from interstitially placed laser fibres varies significantly from the commonly assumed ideal cylindrical emission, a predictive mathematical model of prostate PDT needs to consider the real emission. Also, the optical properties of the prostate, e.g. absorption and scattering of light, are anisotropic. Differences in the attenuation coefficient (combining absorption and scattering of light) also varied among different animals. Incorporating all these variables into a computer program produced a virtual model of the photo-ablated zone within +/- 2 mm of that observed in animals. CONCLUSION: PDT of the prostate is not trivial and should benefit from computer-aided methods as it is developed for clinical use.

Animals↗

PubMed2005

In vivo and in vitro effect of baicalein on human prostate cancer cells.

We investigated the in vitro effects of baicalein and baicalin on human umbilical vein endothelial cells (HUVECs) and on human prostate tumor cells (DU-145 and PC3) as well as the effect of orally administered baicalein on the growth of DU-145 cells after subcutaneous injection into SCID mice. In vitro effects of baicalein and baicalin treatment on human prostate cancer cell lines DU-145 and PC-3 were assessed by employing cell proliferation (MTS) assay, cytotoxicity (LIVE/DEAD) assay, and TUNEL assay. In vitro anti-proliferative and anti-angiogenic properties of baicalein and baicalin were studied on HUVECs by sprout assay. The effect of orally administered baicalein on tumor growth in SCID mice was studied in four groups (n=10) of animals injected subcutaneously with DU-145 cells and treated daily for 28 days. The control group received only vehicle (carboxymethylcellulose), whereas the other three groups received escalating doses of baicalein (10, 20, and 40 mg/kg per day). Baicalein and baicalin exhibit dose-dependent growth inhibitory effects on human prostate cancer cells and umbilical vein endothelial cells in vitro. Also, treatment by these two flavonoid compounds significantly decreased the average number and length of sprouts formed by the endothelial cell aggregates in a dose-dependent manner. In vivo, treatment of mice with baicalein demonstrated a statistically significant tumor volume reduction (p<0.01) when compared to the control. This is the first study demonstrating an in vivo growth inhibitory effect of orally administered baicalein on human prostate tumors in mice.

Administration, Oral↗

PubMed2004

Transperineal in vivo fluence-rate dosimetry in the canine prostate during SnET2-mediated PDT.

Advances in photodynamic therapy (PDT) treatment for prostate cancer can be achieved either by improving selectivity of the photosensitizer towards prostate gland tissue or improving the dosimetry by means of individualized treatment planning using currently available photosensitizers. The latter approach requires the ability to measure, among other parameters, the fluence rate at different positions within the prostate and the ability to derive the tissue optical properties. Here fibre optic probes are presented capable of measuring the fluence rate throughout large tissue volumes and a method to derive the tissue optical properties for different volumes of the prostate. The responsivity of the sensors is sufficient to detect a fluence rate of 0.1 mW cm(-2). The effective attenuation coefficient in the canine prostate at 660 nm is higher at the capsule (2.15+/-0.19 cm(-1)) than in proximity of the urethra (1.84+/-0.36 cm(-1)). Significant spatial and temporal intra- and inter-canine variability in the tissue optical properties was noted, highlighting the need for individualized monitoring of the fluence rate for improved dosimetry.

Algorithms↗

PubMed2004

Soybean lipoxygenase-3 in complex with 4-nitrocatechol.

4-Nitrocatechol (4NC) is a known inhibitor of lipoxygenase. This work presents the X-ray structure of soybean lipoxygenase-3 in complex with 4NC refined at 2.15 A resolution. The X-ray analysis shows 4NC near iron with partial occupancy, blocking access to Fe but not covalently bound to it. The two hydroxyl groups interact with the C-terminus (4-OH) and His523 ND1 (3-OH). The residues surrounding the iron cofactor, His518*, His523, His709, Ile857* COO(-) and water, form a trigonal bipyramid with the residues marked with asterisks in the axial positions. The water bound to iron and the presence of the inhibitor seem to be responsible for the rearrangements and changes in the geometry of the ligand distribution and confirm the displacement of His518 from iron coordination. A description of the catechol binding contributes to the understanding of lipoxygenase inhibition and the participation of its co-oxidative activity in the utilization of natural flavonoids.

Catechols↗

PubMed2004

Lipoxygenase interactions with natural flavonoid, quercetin, reveal a complex with protocatechuic acid in its X-ray structure at 2.1 A resolution.

PUFA metabolites have a profound effect on inflammatory diseases and cancer progression. Blocking their production by inhibiting PUFA metabolizing enzymes (dioxygenases: cyclooxygenases and LOXs) might be a successful way to control and relieve such problems, if we learn to better understand their actions at a molecular level. Compounds with strong antioxidative and free radical scavenging properties, such as polyphenols, could be effective in blocking PUFA activities, and natural flavonoids possess such qualities. Quercetin belongs to the group of natural catecholic compounds and is known as a potent, competitive inhibitor of LOX. Structural analysis reveals that quercetin entrapped within LOX undergoes degradation, and the resulting compound has been identified by X-ray analysis as protocatechuic acid (3,4-dihydroxybenzoic acid) positioned near the iron site. Its C3-OH group points toward His523, C4-OH forms a hydrogen bond with O=C from the enzyme's C-terminus, and the carboxylic group is incorporated into the hydrogen bonding network of the active-site neighborhood via Gln514. This unexpected result, together with our previous observations concerning other polyphenols, yields new evidence about the metabolism of natural flavonoids. These compounds might be vulnerable to the co-oxidase activity of LOX, leading to enzyme-stimulated oxidative degradation, which results in an inhibitor of a lower molecular weight.

Crystallography, X-Ray↗

PubMed2004

Optical characteristics of the canine prostate at 665 nm sensitized with tin etiopurpurin dichloride: need for real-time monitoring of photodynamic therapy.

PURPOSE: Photodynamic therapy (PDT) is an emerging, minimally invasive therapy for prostate cancer that depends on the sequestration of a photosensitizing drug within targeted tissue. The photosensitizer is subsequently activated by light of a specific wavelength, resulting in destruction of the targeted tissue. Successful treatment requires knowledge of the optical properties of the target tissue, a critical element for therapy. MATERIALS AND METHODS: Adult canines were injected with tin etiopurpurin dichloride (1.0 mg/kg) as a liposome emulsion vehicle in saline 24 hours prior to light treatment. Laser light was delivered to the prostate via a 400 microm optical fiber fitted with a 2.0 cm cylindrical diffuser and optical properties of the prostate were measured. RESULTS: In this study we determined the attenuation coefficient and critical fluence in the canine prostate. Our studies shown that the attenuation coefficient is not uniform but higher at the base (average for all animals 2.59 to 2.79 cm-1) than in the mid section or apex of the prostate (1.71 to 1.90 cm-1). Significant differences among dogs (0.11 to 12.70 cm-1) were found. In some cases we observed a fluctuation of the attenuation coefficient during treatment. We also established experimentally the minimum energy (1449 mJ/cm2) needed (critical fluence) to produce necrosis. Experimentally establishing the values of effective attenuation and critical fluence is necessary to predict the area of ablation during PDT and protect surrounding organs from over treatment. CONCLUSIONS: Based on our results it is evident that for PDT of the prostate to be successful the optical parameters of the prostate must be measured and monitored during treatment. We suggest that the optimum way of doing this is real-time computerized monitoring combined with simulation PDT.

Animals↗

PubMed2004

Plasminogen activator inhibitor type-1: its structure, biological activity and role in tumorigenesis (Review).

Plasminogen activator inhibitor type-1 (PAI-1), is a unique member of serpin superfamily, the primary regulator of plasminogen activation and therefore essential factor regulating physiological thrombotic/fibrinolytic balance in vivo. Via interactions with integrins and extracellular matrix components it orchestrates also cell adhesion and migration. Therefore, PAI-1 is considered one of the key regulators of tumor invasion and metastasis, as well as cancer-related angiogenesis. This review summarizes recent findings on the structure and functional activity of the plasminogen activator inhibitor type-1, and current opinions on its role in tumorigenesis.

Animals↗

PubMed2004

Plasminogen activator inhibitor type-1 mutants regulate angiogenesis of human umbilical and lung vascular endothelial cells.

Plasminogen activator inhibitor type-1 (PAI-1) is considered one of the key regulators of tumor invasion, metastasis, as well as cancer-related angiogenesis. The literature suggests that PAI-1 plays a dual role in these processes because it inhibits plasmin-originated proteolysis and binds to vitronectin or integrins. Stimulation or inhibition of angiogenesis largely depends on which of these elements PAI-1 interacts. Wild PAI-1 converts quickly into its latent, inactive form and loses its anti-proteolytic activity, but still binds to vitronectin and integrins. Thus we constructed PAI-1s with extended half-life to prolong their anti-proteolytic activity. We have analyzed the effects of sprout formation inhibition by PAI-1s on two functionally different endothelial cell (EC) systems, human umbilical vein endothelial cells (HUVEC), expressing moderate amounts of urokinase (uPA), and human lung microvascular endothelial cells (HLMVEC), expressing high amounts of this enzyme. We have used wild-type PAI-1 (wPAI-1) (t(1/2) = 1.6 h) and PAI-1 cysteine mutants (CysPAI-1) characterized by their prolonged half-life time (hDbetaT) (t(1/2) = 63.6 h and t(1/2) = 7,000 h). We have observed a significant inhibitory dose-dependent effect exerted by the CysPAI-1s on sprout formation by HUVEC and HLMVEC cells. The inhibition rate was considerably stronger in lung capillary cell cultures and significantly more pronounced for CysPAI-1 mutants with longer anti-uPA activity (betaT). wPAI-1 with a short anti-proteolytic half-life has induced sprout formation in HUVEC, but not in HLMVEC cultures. This difference in behavior was most likely related to the presence of excessive amounts of uPA in HLMVEC cells and the known mechanism of clearing PAI-1/uPA/uPAR complexes from the cell surface. A less efficient system of HUVEC cells might give wPAI-1 the chance to interact with non-proteolytic pathways of angiogenesis stimulation. We conclude that while the anti-proteolytic properties of PAI-1 constructs are preserved, these proteins inhibit angiogenesis and inhibitory activity dominates over any stimulatory effects of PAI-1.

Cells, Cultured↗

PubMed2003

Computer simulation of prostate cryoablation--fast and accurate approximation of the exact solution.

OBJECTIVE: Cryosurgery is a minimally invasive cancer treatment that uses liquid nitrogen or supercooled argon to freeze and destroy tumors. To achieve complete ablation of the prostate, we have developed a computer program that can determine treatment effects by calculating iceball formation. This is based on a three-dimensional (3D) model of the patient's prostate constructed from ultrasound images. The program predicts the best set of cryoablation parameters and cryoprobe spatial positions, then displays these parameters in graphical or numerical form. The objective of this work was to improve our prostate cryoablation modeling software by making its partial differential equation (PDE) solver more accurate and faster. MATERIALS AND METHODS: CryoSim, our software package, accepts a set of acquired and processed 3D ultrasound images of the prostate, then models heat diffusion using numerical approximations of the heat equation. RESULTS: We describe the latest version of the CryoSim software, which models cryoablation therapy. Solving the problems of low spatial resolution (now down to a fraction of a millimeter, as compared to 5 mm in the old version) and modeling cryosurgery in a short time (down to few minutes versus hours) provides a platform for proper planning of cryosurgery and a tool for the training of surgeons. CONCLUSION: Changes in the PDE solver algorithm produce more accurate results, leading to an improved visualization of the iceball, with a precision of a few mm and a significant decrease in computation time.

Algorithms↗

PubMed2003

A novel form of the plasminogen activator inhibitor created by cysteine mutations extends its half-life: relevance to cancer and angiogenesis.

Proteolytic activity driven by urokinase (uPA) is commonly recognized as an important factor in metastasis and angiogenesis. The eradication of unwanted uPA activity expressed by cancer cells results in the inhibition of metastasis and angiogenesis. Development of novel and highly selective uPA inhibitors could, therefore, produce new treatments of cancer. The ultimate goal of this work is the identification of novel and selective inhibitors of uPA suitable for this purpose. We have chosen plasminogen activator inhibitor(s) type 1 (PAI-1), which selectively inhibits the urokinase plasminogen activator (uPA). However, PAI-1 is not a stable molecule and converts itself into the latent form with a half-life in the range of t1/2 = 1-2 h. This conversion is associated with a partial insertion of the reactive loop (P4-P10') into the PAI-1 molecule. In such a conformation, P1-P1' and other sites are not accessible for reaction with uPA. To conquer this hurdle, we have produced several PAI-1 mutants by replacing chosen amino acids with cysteine in the hope of creating disulfide bridges, which could make this insertion more difficult. On the basis of the known structure of active PAI-1, we have identified amino acids that can be substituted with a cysteine residue to produce disulfide bridges linking the top and bottom parts of strands A3 and A5 as well as sites within the helix-D region. We created a total of seven cysteine mutants via point mutation (two to six point mutations), generating possible sites for disulfide bridge formation at the top and bottom parts of A3 and A5, within the helix-D region, or by a combination thereof. Desired mutations were introduced by PCR using appropriate primers. The mutant forms of PAI-1 containing the chitin-binding intein tag were then purified using affinity chromatography wherein the intein tag is cleaved, leaving mutant PAI-1 protein. Cys mutations resulted in proteins with extended half-life of PAI-1 from 2 to >700 h depending on the mutant. Novel PAI-1 were fully functional against uPA and showed activity in the in vitro model of angiogenesis, e.g., in the inhibition of sprout formation. Such prolonged serpin activity, which is therapeutically desired in cancer treatment and Cys-mutated PAI-1, could launch a new class of novel anticancer agents.

Amino Acid Sequence↗

PubMed2003

Spatial distribution of liposome encapsulated tin etiopurpurin dichloride (SnET2) in the canine prostate: implications for computer simulation of photodynamic therapy.

Photodynamic therapy (PDT) is a minimally invasive treatment that can be employed in many human diseases including prostate cancer. PDT for prostate cancer depends on the sequestration of a photosensitizing drug within the glandular tissue. The photosensitizer is subsequently activated by light (usually from a laser) and the active drug destroys tissue. Since prostate cancer is a multifocal disease, PDT must ablate the glandular prostate completely. This will depend on the precise placement of light sources in the prostate and delivery of a therapeutic light dose to the entire gland. Also, sources of light and their spatial distribution must be tailored to each individual patient. The uniform, therapeutic light distribution can be achieved by interstitial light irradiation. In this case, the light is delivered by diffusers placed within the substance of the prostate parallel to the urethra at a distance optimized to deliver adequate levels of light and to create the desired photodynamic effect. To help achieve the uniform light distribution throughout the prostate we have developed a computer program that can determine treatment effects. The program predicts the best set of parameters and the position of light diffusers in space, and displays them in graphical or in numerical form assuming a fixed attenuation coefficient. The two parameters of greatest importance in the computer simulation are attenuation coefficient and critical fluence. Both depend on the concentration of active drug within the prostate gland. It is necessary to know the nature of the spatial distribution of photosensitizer within the prostate to execute computer modeling of PDT with high precision. We found that the concentration of SnET2 is heterogeneous in nature, and is higher in the proximity of the glandular capsule. It is clear therefore that any future attempts of computerized modeling of this procedure must take into consideration the uneven sequestration of photosensitizer and the consequential asymmetrical necrosis of the prostate.

Algorithms↗

PubMed2003

Structure of curcumin in complex with lipoxygenase and its significance in cancer.

Scientific research provides documented evidence that fatty acid metabolites have profound impact on carcinogenesis. Intervention into dioxygenase pathways might therefore effect development, metastasis and progression of many types of cancers. This work delivers the first 3D structural data and explains how curcumin interacts with the fatty acid metabolizing enzyme, soybean lipoxygenase. Curcumin binds to lipoxygenase in a non-competitive manner. Trapped in that complex, it undergoes photodegradation in the X-rays, but utilizes enzyme catalytic ability to form the peroxy complex Enz-Fe-O-O-R as 4-hydroperoxy-2-methoxy-phenol, that later transforms into 2-methoxycyclohexa-2,5-diene-1,4-dione. Our observations about this radiation and time-dependent inhibition add new information to the role that curcumin might play in cancer prevention and treatment.

Animals↗

PubMed2003

Inhibition of lipoxygenase by (-)-epigallocatechin gallate: X-ray analysis at 2.1 A reveals degradation of EGCG and shows soybean LOX-3 complex with EGC instead.

Lipoxygenases (LOXs) are non-heme iron containing enzymes ubiquitous in nature and participating in the metabolism of the polyunsaturated fatty acids (PUFA). They are capable of combining their dioxygenase activity with its co-oxidative activity manifesting itself in biotransformation reactions catalyzed by LOXs for other than PUFA small molecules. LOXs involvement in inflammatory diseases and cancer have been well documented. Catechins are the natural flavonoids of known inhibitory activity toward dioxygenases with a potential to be utilized in disease prevention and treatment. This work presents results obtained from an X-ray analysis of (-)-epigallocatechin gallate (EGCG) interacting with soybean lipoxygenase-3. The 3D structure of the resulting complex reveals the inhibitor depicting (-)-epigallo-catechin that lacks galloyl moiety. The A-ring is near the iron co-factor, attached by the hydrogen bond to the C-terminus of the enzyme, and the B-ring hydroxyl groups participate in the hydrogen bonds and the van der Waals interactions formed by the surrounding amino acids and water molecules.

Animals↗