High Affinity Constant Research Articles

Strong light-trapping probes with high antibody activity for sensitive detecting FB1 by “turn-on” lateral flow immunoassay

Due to the insufficient chromaticity, traditional Au nanoparticles (AuNPs) are usually unsatisfactory in the lateral flow immunoassay (LFIA) for tracing targets. Polypyrrole nanoparticles (PPyNPs), known for their excellent optical properties, have a limited chemical surface, which is unsuitable for use in LFIA. PPyNPs@metal-phenolic materials (PMNPs) were designed to break the restriction, which were then applied in fluorescence quenching LFIA to detect fumonisin B1 (FB1). PMNPs, as an efficient fluorescence quencher, with strong absorption in the ultraviolet–visible region, had the molar extinction coefficient of 2.47 × 1011 M−1 cm−1 and 1.86 × 1011 M−1 cm−1 at 335 nm and 620 nm. Meanwhile, the quenching constant of PMNPs was 2.30 × 10−10, 23.6-fold higher than that of AuNPs. After the surface modification with the Au-TA structure, PMNPs exhibited higher hydrophilicity than PPyNPs, making them more favorable to antibody binding. Compared with AuNPs-mAb and PPyNPs-mAb, the PMNPs-mAb had a higher affinity constant and lower equilibrium dissociation constant. The visual limit of detection (vLOD) and LOD of the “turn-on” LFIA based on PMNPs were 25 ng mL−1 and 1.58 ng mL−1, which were 20-fold and 4.82-fold lower than that of AuNPs-LFIA, respectively. Furthermore, the method demonstrated satisfactory recoveries in detecting FB1 in food samples, confirmed by LC-MS.

Industrial grade calcium sulfide modified by selenium for elemental mercury removal from flue gas

Metallic sulfides (MS) adsorption is considered as an effective method to remove Hg0 from coal-fire flue gas. Se modification can significantly improve Hg0 removal process on MS due to the high affinity constant between Se and Hg0. CaS as a production from wet flue gas desulfurization has potential Hg0 removal ability. Therefore, in the present work, Se modified industrial grade CaS was prepared to remove Hg0 and the effect of the ratio of CaS to Se on Hg0 removal process was studied. Characterization results show that Ca1-Se1.7 had the richest porous structure and largest surface area resulting in more available surface active sites. In addition, Ca1-Se1.7 has the highest content of Se−, who can remove Hg0 via Hg0(ad)+Se22-→HgSe+Se2-. As a result, Ca1-Se1.7 has the highest Hg0 removal efficiency of nearly 100 % from 60 ℃ to 100 ℃, and it reaches 85 % even in the presence of 500 ppm SO2. The Hg0 adsorption kinetic was well defined by the pseudo-first-order kinetic model and internal diffusion model, so that Hg0 diffusion especially internal diffusion is the primary controlling step.

Identification of a New B-Cell Epitope on the Capsid Protein of Avian Leukosis Virus and Its Application.

Avian leukosis virus (ALV) is an avian oncogenic retrovirus that can impair immunological function, stunt growth and decrease egg production in avian flocks. The capsid protein (P27) is an attractive candidate for ALV diagnostics. In the present study, a new hybridoma cell (1F8) stably secreting an anti-P27 monoclonal antibody (mAb) was developed. The mAb exhibited a high affinity constant (Ka) of 8.65 × 106.0 L/mol, and it could be used for the detection of ALV-A/B/J/K strains. Moreover, a total of eight truncated recombinant proteins and five synthetic polypeptides were utilized for the identification of the B-cell epitopes present on P27. The results revealed that 218IIKYVLDRQK227 was the minimal epitope recognized by 1F8, which had never been reported before. Additionally, the epitopes could strongly react with different ALV subgroup's specific positive serum and had a complete homology among all the ALV subgroups strains. Finally, a new sandwich ELISA method was created for the detection of ALV antigens, demonstrating increased sensitivity compared to a commercially available ELISA kit. These results offer essential knowledge for further characterizing the antigenic composition of ALV P27 and will facilitate the development of diagnostic reagents for ALV.

Ammonium-based bioleaching of toxic metals from sewage sludge in a continuous bioreactor

The broader reuse of sewage sludge as a soil fertilizer or conditioner is impeded by the presence of toxic metals. Bioleaching, a process that leverages microbial metabolisms and metabolites for metal extraction, is viewed as an economically and environmentally feasible approach for metal removal. This study presents an innovative bioleaching process based on microbial oxidation of ammonia released from sludge hydrolysis, mediated by a novel acid tolerant ammonia-oxidizing bacteria (AOB), Ca. Nitrosoglobus. Over a span of 1024 days, a laboratory-scale bioleaching reactor processing anaerobically digested (AD) sludge achieved an in-situ pH of 2.5 ± 0.3. This acidic environment facilitated efficient leaching of toxic metals from AD sludge, upgrading its quality from Grade C to Grade A (qualified for unrestricted use), according to both stabilization and contaminants criteria. The improved quality of AD sludge could potentially reduce sludge disposal expenses and enable a broader reuse of biosolids. Furthermore, this study revealed a pH-dependent total ammonia affinity of Ca. Nitrosoglobus, with a higher affinity constant at pH 3.5 (67.3 ± 20.7 mg N/L) compared to pH 4.5–7.5 (7.6 – 9.6 mg N/L). This finding indicates that by optimizing ammonium concentrations, the efficiency of this novel ammonium-based bioleaching process could be significantly increased.

Computational study of the piperidine and FtsZ interaction in Salmonella Typhi: implications for disrupting cell division machinery

FtsZ, a bacterial cell division protein, is essential for assembling the contractile Z-ring crucial in bacterial cytokinesis. Consequently, inhibiting FtsZ could impede proto-filaments, disrupting FtsZ and other associated proteins vital for cell division machinery. Conduct an in-silico drug interaction study to identify novel drug candidates that inhibit the FtsZ protein, aiming to prevent Multi-Drug Resistant (MDR) Salmonella Typhi. Data mining was performed based on piperidine compounds, which were subsequently screened for safe pharmacokinetic profiles. Compounds that met favorable drug-likeness criteria underwent virtual screening against the FtsZ drug target. Two compounds were chosen for molecular docking and molecular dynamic simulation to verify the binding affinity and stability between the target protein and the potential compounds. The 400 isoforms of piperidine analogues were curated, among them potent compound ZINC000000005416 found to possess high binding affinity (-8.49 kcal/mol) and low dissociation constant (0.597 µM). The highest binding affinity shown by ZINC000000005416 was validated by hydrogen bonds, hydrophobic interaction, and salt bridges with the functional domain of the cell division regulatory protein. Docking profiles, when correlated with molecular dynamic simulation (MDS) depicted stable trajectories and compatible conformational changes in the FtsZ-ZINC000000005416 complex. The stable simulated trajectories were validated through free-energy calculations using the Molecular Mechanics-Poisson Boltzmann Surface Area (MM/PBSA) module. Low energy conformations, although the simulation trajectory confirmed the stable ZINC000000005416-FtsZ interaction, which encouraged experimental validations. This study encourages further exploration of the compound ZINC000000005416 as a drug candidate inhibiting FtsZ protein against MDR Salmonella Typhi. Communicated by Ramaswamy H. Sarma

Characterization and stabilization of GluLm and its application to deglycosylate dietary flavonoids and lignans

This study describes the characterization of the recombinant GH3 aryl-β-glucosidase “GluLm” from Limosilactobacillus mucosae INIA P508, followed by its immobilization on an agarose support with the aim of developing an efficient application to increase the availability and concentration of flavonoid and lignan aglycones in a vegetal beverage. In previous studies, heterologous GluLm-producing strains demonstrated a great capacity to deglycosylate flavonoids. Nevertheless, the physicochemical properties and substrate spectrum of the enzyme remained unknown up to now. A high production of purified GluLm was achieved (14 mg L−1). GluLm exhibited optimal activity at broad ranges of pH (5.0–8.0) and temperature (25–60°C), as well as high affinity (Km of 0.10 mmol L−1) and specific constant (86554.0 mmol L−1 s−1) against p-nitrophenyl-β-D-glucopyranoside. Similar to other GH3 β-glucosidases described in lactic acid bacteria, GluLm exhibited β-xylosidase, β-galactosidase, and β-fucosidase activities. However, this study has revealed for the first time that a GH3 β-glucosidase is capable to hydrolyze different families of glycosylated phenolics such as flavonoids and secoiridoids. Although it exhibited low thermal stability, immobilization of GluLm improved its thermostability and allowed the development of a beverage based on soybeans and flaxseed extract with high concentration of bioactive isoflavone (daidzein, genistein), lignan (secoisolariciresinol, pinoresinol, and matairesinol), and other flavonoid aglycones.Key points• Limosilactobacillus mucosae INIA P508 GluLm was purified and biochemically characterized• Immobilized GluLm efficiently deglycosylated flavonoids and lignans from a vegetal beverage• A viable application to produce vegetal beverages with a high content of aglycones is described

A sensitive and rapid method of lead detection using nanoparticle technology based on monoclonal antibody.

Lead (Pb) threatens public health due to its toxicity and nonbiodegradable characteristics. It is of significance to develop a sensitive and rapid method for Pb detection. In this study, monoclonal antibodies against Pb were screened with a high affinity constant (Kaff) of 3.56 × 109 L/mol. Au nanosphere particles (AuNS) and Au nanoflower particles (AuNF) were synthesized with a diameter of 15 nm and 60 nm, respectively. The specific anti-Pb antibodies were then immobilized on AuNS and AuNF for probe development. At last, AuNS- and AuNF-based strips were successfully assembled for comparative study, which were able to effectively detect environmental Pb in 10 min. The limits of detection (LODs) were determined to be 3.91 ng/ml and 0.2 ng/ml, respectively. Thus the developed method provides a feasible solution for sensitive and rapid detection of Pb on site, which is beneficial to food safety and pollution control.

An Optical Fiber Sensor for Uranium Detection in Water.

An optical sensor for uranyl has been prepared based on a gold-plated D-shaped plastic optical fiber (POF) combined with a receptor consisting of a bifunctional synthetic molecule, 11-mercaptoundecylphosphonic acid (MUPA), with a phosphonic group for complexing the considered ion, and a sulfide moiety through which the molecule is fixed at the gold resonant surface as a molecular layer in an easy and reproducible way. The sensor is characterized by evaluating the response in function of the uranyl concentration in aqueous solutions of different compositions and real-life samples, such as tap water and seawater. The mechanism of the uranyl/MUPA interaction was investigated. Two different kinds of interactions of uranyl with the MUPA layer on gold from water are observed: a strong one and a weak one. In the presence of competing metal ions as Ca2+ and Mg2+, only the strong interaction takes place, with a high affinity constant (around 107 M−1), while a somewhat lower constant (i.e., around 106 M−1) is obtained in the presence of Mg2+ which forms stronger complexes with MUPA than Ca2+. Due to the high affinity and the good selectivity of the recognition element MUPA, a detection limit of a few μg L−1 is reached directly in natural water samples without any time-consuming sample pretreatment, making it possible for rapid, in situ controls of uranyl by the proposed sensor.

Consensus Enolase of Trypanosoma Cruzi: Evaluation of Their Immunogenic Properties Using a Bioinformatics Approach.

There is currently no vaccine against American trypanosomiasis, caused by the parasite Trypanosoma cruzi. This is due to the genomic variation observed in the six DTUs of T. cruzi. This work aims to propose a consensus sequence of the enolase protein from different strains of T. cruzi and mainly evaluate its immunogenic properties at the bioinformatic level. From specialized databases, 15 sequences of the enolase gene were aligned to obtain a consensus sequence, where this sequence was modeled and then evaluated and validated through different bioinformatic programs to learn their immunogenic potential. Finally, chimeric peptides were designed with the most representative epitopes. The results showed high immunogenic potential with six epitopes for MHC-I, and seven epitopes for MHC-II, all of which were highly representative of the enolase present in strains from the American continent as well as five epitopes for B cells. Regarding the computational modeling, molecular docking with Toll-like receptors showed a high affinity and low constant of dissociation, which could lead to an innate-type immune response that helps to eliminate the parasite. In conclusion, the consensus sequence proposed for enolase is capable of providing an ideal immune response; however, the experimental evaluation of this enolase consensus and their chimeric peptides should be a high priority to develop a vaccine against Chagas disease.

Sensitive Electrochemical Detection of Phosphorylated-Tau Threonine 231 in Human Serum Using Interdigitated Wave-Shaped Electrode.

The development of an electrochemical biosensor for the detection of phosphorylated-tau threonine 231 (p-tau231), a biomarker of Alzheimer’s disease (AD), has yet to be achieved. Therefore, in this study, we developed a simple, small size, cheap, and sensitive electrochemical biosensor based on an interdigitated wave-shaped electrode via an activated self-assembled monolayer to preserve a specific anti–p-tau231 antibody (IWE/SAM/EDC-NHS/anti–p-tau231). Detection of p-tau231 in human serum (HS) using the biosensor was undertaken using electrochemical impedance spectroscopy (EIS). The change in charge-transfer resistance (Rct) in the EIS analysis of the biosensor indicated the detection of p-tau231 in HS within a wide linear range of detection (10−4–101 ng mL−1), and a low limit of detection (140 pg mL−1). This lower limit is less than the detection level of p-tau231 in cerebrospinal fluid (CSF) (700 pg mL−1) of AD patients and the level of CSF p-tau231 of patients with mild cognitive impairment (501 pg mL−1), demonstrating the possibility of using the biosensor in detection of p-tau231 at early stage AD. A high binding affinity and low dissociation constant (Kd) between anti–p-tau231 and p-tau231 in HS was demonstrated by using a biosensor and Kd was 7.6 pM, demonstrating the high specific detection of p-tau231 by the biosensor. The good selectivity of the biosensor for the detection of p-tau231 with differential analytes was also examined in this study.

Label-free electrochemical detection of genetic damage induced by the interaction of a novel potential aminoanthraquinone-derived antitumor agent with DNA modified electrode

In this work, an efficient electrochemical biosensor for the detection of DNA damage induced by the interaction of a novel antitumor agent AD-NU was investigated by CV, DPV and SWV methods. The GCE was modified with calf thymus DNA, G-quadruplexes, poly dA and poly dG, respectively. Among all the candidates, compound AD-NU was the optimum ligand because of the minimum energy when binding to DNA or TOP II by molecular docking. The electrochemical analysis revealed the redox mechanism of AD-NU on the GCE surface, which included two consecutive reversible processes of 9,10-diquinone and irreversible redox of nitroso group. The DNA damage caused by AD-NU was investigated by comparing the intensity changes of dGuo and dAdo oxidation peaks in DNA strands, and monitoring the appearance of peak for oxidative product 8-oxoGua. Further confirmation for the interaction between AD-NU and DNA was performed by UV–vis absorption and fluorescence titration, which implied the intercalation of AD-NU into DNA base pairs with a high affinity constant (Kb = 13.7 ×105 M−1). The electrophoresis also revealed the potency of AD-NU to cleave and unwind DNA strands. Finally, AD-NU was proved to have good antiproliferative activity toward tumor cells, with IC50 values of 3.0 μmol∙L−1 for A549 cell lines and 3.3 μmol∙L−1 for Hela cell lines, superior to MTZ reference.

Structural and Thermodynamics Studies on Polyaminophosphonate Ligands for Uranyl Decorporation.

The development of actinide decorporation agents with high complexation affinity, high tissue specificity, and low biological toxicity is of vital importance for the sustained and healthy development of nuclear energy. After accidental actinide intake, sequestration by chelation therapy to reduce acute damage is considered as the most effective method. In this work, a series of bis- and tetra-phosphonated pyridine ligands have been designed, synthesized, and characterized for uranyl (UO22+) decorporation. Owing to the absorption of the ligand and the luminescence of the uranyl ion, UV-vis spectroscopy and time-resolved laser-induced fluorescence spectroscopy (TRLFS) were used to probe in situ complexation and structure variation of the complexes formed by the ligands with uranyl. Density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) spectroscopy on uranyl-ligand complexes revealed the coordination geometry around the uranyl center at pH 3 and 7.4. High affinity constants (log K ∼17) toward the uranyl ion were determined by displacement titration. A preliminary in vitro chelation study proves that bis-phosphonated pyridine ligands can remove uranium from calmodulin (CaM) at a low dose and in the short term, which supports further uranyl decorporation applications of these ligands.

Identification, purification and characterization of a novel glycosidase (BgLm1) from Leuconostoc mesenteroides

This study describes the identification and characterization of a novel recombinant Leuconostoc mesenteroides glycosidase (BgLm1). Since the protein encoded by LEUM_0847 gene was annotated as putative β-glucosidase, characterization procedures were done using p-nitrophenyl-β-d-glucopyranoside as substrate. A high yield of purified recombinant BgLm1 was obtained (12 mg/L). The enzyme showed an optimal activity at pH 6.0 and 40 °C and preserved 65% of residual activity after 48 h of incubation at 25 °C. Ca2+ and Mn2+ ions greatly increased the β-glucosidase activity. Moreover, BgLm1 demonstrated β-galactosidase and β-fucosidase activities. Kinetic parameters of BgLm1 revealed its low affinity to p-nitrophenyl-β-d-glucopyranoside (Km of 9.93 mmol/L).Then, although LEUM_0847 gene was annotated as a β-glucosidase, our results suggest that BgLm1can be indeed considered as a β-galactosidase since high hydrolysis using skimmed milk (lactose) as natural substrate and high affinity (Km of 0.56 mmol/L) and specific constant (2254 mmol/L−1 s−1) to p-nitrophenyl-β-d-galactopyranoside were observed. In conclusion, the enzymatic properties observed in this study, support the interest of BgLm1 for food industrial applications.

Selection and characterization of ssDNA aptamers specifically recognizing pathogenic Vibrio alginolyticus

Vibrio alginolyticus (V.alginolyticus) is a major opportunistic pathogen to both marine animals and humans, which has also caused heavy economic losses to mariculture. The aim of this study was to develop highly specific aptamers for V.alginolyticus. Single-stranded DNA (ssDNA) aptamers with high binding affinity to viable V.alginolyticus were generated by Systematic Evolution of Ligands by Exponential Enrichment (SELEX) and identified by flow cytometric analysis in this study. The selected aptamers showed high specificity for V.alginolyticus and low apparent binding for other bacteria. The aptamers formed distinct stem-loop structures, which could form the basis of aptamers' specific binding to the target V.alginolyticus. Aptamer VA2 and VA8 showed particularly high binding affinity constant (Kd) of 14.31±4.26 and 90.00±13.51nM, respectively. The aptamers produced no cytotoxic effects in vitro and in vivo. ssDNA aptamers were successfully selected against the viable bacteria pathogen V.alginolyticus by SELEX. The aptamers selected in this study could be not only applied as specific chemical molecular probes for studying V.alginolyticus pathogenesis to Trachinotus ovatus, but also developing rapid convenient diagnosis assay for V.alginolyticus infection, even when applied to the complex sample matrix, such as food and environment samples.

Diagnosis of hepatocellular carcinoma using a novel anti-glycocholic acid monoclonal antibody-based method.

Glycocholic acid (GCA) is a novel identified biomarker for hepatocellular carcinoma (HCC). However, clinical pathological study of GCA has not been extensive due to the limited availability of anti-GCA monoclonal antibodies (mAbs) and restricted detection methods. In the present study, using human GCA conjugated with bovine serum albumin as the immunogen to immunize BALB/c mice, a novel anti-GCA mAb was generated and characterized. The isotypes of heavy chain and light chain of anti-GCA mAb were examined to be IgG2a and κ, respectively, with a high affinity constant (2.6×108 mol/l). The anti-GCA mAb binds GCA with high specificity and sensitivity, and the 50% inhibitory rate was 77.09 ng/ml. The present study also established a rapid, sensitive and efficient indirect competitive ELISA analysis using this anti-GCA mAb to detect the level of GCA produced by different HCC cell lines. Therefore, the present study may successfully develop a novel method for early HCC diagnosis, and also provide insights for further research and treatment of HCC.

NMR study on the stabilization and chiral discrimination of sulforaphane enantiomers and analogues by cyclodextrins

Sulforaphane (SFN), a phytochemical isolated from broccoli, is an important antitumoral compound with additional beneficial effect on other important diseases. However, the chemical instability of SFN has hampered its clinical use. In order to circumvent this problem, we report the first comparative study on the inclusion complexes of SFN and SFN homologues with different cyclodextrins by NMR spectroscopy. From this study it has been shown that α-CD is the most indicated cyclodextrin for the stabilization of SFN and SFN homologues, and that the highest affinity constant is that of the isothiocyanate obtained from the wasabi. Furthermore, the study of the inclusion complexes of α-CD and the non-natural SFN and analogues with S absolute configuration at sulfur shows for the first time that α-CD is able to discriminate between the two enantiomers, with the natural R enantiomers forming the inclusion complexes with higher affinity.

Multivalent oleanolic acid human serum albumin conjugate as nonglycosylated neomucin for influenza virus capture and entry inhibition

We report the synthesis of multivalent oleanolic acid (OA) protein conjugates as nonglycosylated neomucin mimic for the capture and entry inhibition of influenza viruses. Oleanolic acid derivatives bearing an amine-terminated linker were synthesized by esterification of carboxylic acid and further grafted onto the human serum albumin (HSA) via diethyl squarate method. The binding of hemagglutinin (HA) on the virion surface to the synthetic neomucin was evaluated by hemagglutination inhibition assay. The influenza virus capture ability of the PEGylated OA-HSA conjugate was further investigated by Dynamic Light Scattering (DLS), virus capture assay and Isothermal Titration Calorimeter (ITC) techniques. The pronounced agglutination of viral particles, the high capture efficiency and affinity constant indicate that this neoprotein is comparable to natural glycosylated mucin, suggesting that this material could potentially be used as anti-infective barriers to prevent virus from invading host cells. The study also rationalizes the feasibility of antiviral drug development based on OA or other antiviral small molecules conjugated protein strategies.

Druggability and Binding Site Interaction Studies of Potential Metabolites Isolated from Marine Sponge Aurora globostellata against Human Epidermal Growth Factor Receptor-2.

To study the involvement of compounds stigmasterol and oleic acid isolated from marine sponge Aurora globostellata and docking against the Human Epidermal Growth Factor Receptor-2 in breast cancer. The comparative molecular docking was performed with the natural compounds from marine sponge and the synthetic drugs used in breast cancer treatment against the target HER2. The molecular docking analysis was done using GLIDE in Schrodinger software package. The ADME properties were calculated using the Qikprop. The observation of the common binding site for all the ligands confirms the binding pocket; where the isolated compound Stigmasterol agrees well with the binding residues and thus can be optimized further to arrive at a molecule that has a high binding affinity and low binding constant. The results of the docking studies carried out on HER2 provide an insight for the compound stigmasterol to have drug like properties than oleic acid. These results are supportive to confirm the marine sponges as a better lead for cancer therapeutics.

Chiroplasmonic assemblies of gold nanoparticles as a novel method for sensitive detection of alpha-fetoprotein

Serum alpha-fetoprotein (AFP) is present in enhanced concentrations in patients with liver cancer. Thus, sensitive detection of AFP plays an important role in the early diagnosis and treatment of cancer. In this study, a novel chiroplasmonic assay is presented for the determination of AFP. It is based on (a) the use of DNA-induced chiroplasmonic assemblies of gold nanoparticles (AuNPs) and (b) the high specificity and affinity constants between AFP and its aptamer. First, the AFP aptamer is hybridized with its complementary sequence immobilized on AuNP. As a result, the DNA-modified AuNPs are assembled to form AuNPs dimers which display strong chiroptical activity. If, however, AFP is added, it will bind to the aptamer and this results in a destruction of the aptamer-DNA hybrid and a reduction of the CD signal. Under optimized conditions, the CD intensity drops linearly with the log of the concentration of AFP in the range from 0.02 to 5 ng⋅mL−1. Compared to the established method, this assay does not require bisulfite conversion, PCR amplification or separation. Amounts as low as 11 pg⋅mL−1 (S/N = 3) AFP can be detected. The method was applied to spiked human serum samples and gave recoveries ranging from 92.0% to 106%, and the relative standard derivations ranged from 4.6% to 6.3%. To the best of our knowledge, this is the first chirality based assay for AFP.

In vitro metabolism of benzo[a]pyrene-7,8-dihydrodiol and dibenzo[def,p]chrysene-11,12 diol in rodent and human hepatic microsomes

Polycyclic aromatic hydrocarbons (PAHs) are contaminants that are ubiquitously found in the environment, produced through combustion of organic matter or petrochemicals, and many of which are procarcinogens. The prototypic PAH, benzo[a]pyrene (B[a]P) and the highly carcinogenic dibenzo[def,p]chrysene (DBC) are metabolically activated by isoforms of the P450 enzyme superfamily producing benzo[a]pyrene-7,8-dihydrodiol (B[a]P diol), dibenzo[def,p]chrysene-11,12 diol (DBC diol). Each of these diols can be further metabolized by cytochrome P450 enzymes to highly reactive diol-epoxide metabolites that readily react with DNA or by phase II conjugation facilitating excretion. To complement prior in vitro metabolism studies with parent B[a]P and DBC, both phase I metabolism and phase II glucuronidation of B[a]P diol and DBC diol were measured in hepatic microsomes from female B6129SF1/J mice, male Sprague-Dawley rats, and female humans. Metabolic parameters, including intrinsic clearance and Michaelis-Menten kinetics were calculated from substrate depletion data. Mice and rats demonstrated similar B[a]P diol phase I metabolic rates. Compared to rodents, human phase I metabolism of B[a]P diol demonstrated lower overall metabolic capacity, lower intrinsic clearance at higher substrate concentrations (>0.14μM), and higher intrinsic clearance at lower substrate concentrations (<0.07μM). Rates of DBC diol metabolism did not saturate in mice or humans and were highest overall in mice. Higher affinity constants and lower capacities were observed for DBC diol glucuronidation compared to B[a]P diol glucuronidation; however, intrinsic clearance values for these compounds were consistent within each species. Kinetic parameters reported here will be used to extend physiologically based pharmacokinetic (PBPK) models to include the disposition of B[a]P and DBC metabolites in animal models and humans to support future human health risk assessments.