Shape of Testosterone

Unbiased Comparison between Theoretical and Experimental Molecular Structures and Properties: Toward an Accurate Reduced-Cost Evaluation of Vibrational Contributions

The tremendous development of hardware and software is constantly increasing the role of quantum chemical (QC) computations in the assignment and interpretation of experimental results. However, an unbiased comparison between theory and experiment requires the proper account of vibrational averaging effects. In particular, high-resolution spectra in the gas phase are now available for molecules containing up to about 50 atoms, which are too large for a brute-force approach with the available QC methods of sufficient accuracy. In the present paper, we introduce hybrid approaches, which allow the accurate evaluation of vibrational averaging effects for molecules of this size beyond the harmonic approximation, with special attention being devoted to rotational constants. After the validation of new tools for relatively small molecules, the β-estradiol hormone and a prototypical molecular motor have been considered to witness the feasibility of accurate computations for large molecules.

Accurate Structures and Rotational Constants of Steroid Hormones at DFT Cost: Androsterone, Testosterone, Estrone, β-Estradiol, and Estriol

A comprehensive analysis of the structural, conformational, and spectroscopic properties in the gas phase has been performed for five prototypical steroid hormones, namely, androsterone, testosterone, estrone, β-estradiol, and estriol. The revDSD-PBEP86 double-hybrid functional in conjunction with the D3BJ empirical dispersion and a suitable triple-ζ basis set provides accurate conformational energies and equilibrium molecular structures, with the latter being further improved by proper account of core-valence correlation. Average deviations within 0.1% between computed and experimental ground state rotational constants are reached when adding to those equilibrium values vibrational corrections obtained at the cost of standard harmonic frequencies thanks to the use of a new computational tool. Together with the intrinsic interest of the studied hormones, the accuracy of the results obtained at DFT cost for molecules containing about 50 atoms paves the way toward the accurate investigations of other flexible bricks of life.

Revealing the Structure of 6-Aminopenillanic Acid: The Active Nucleus of Penicillins

6-Aminopenicillanic acid is a penicillanic acid compound and is the active nucleus common to all penicillins. Using laser ablation techniques, we transformed the solid into the gas phase and characterized its conformational panorama by combining supersonic expansions and Fourier transform microwave techniques. Five conformers were determined, adopting different spatial configurations. Among them, the axial and equatorial forms, which are biologically relevant, have been observed. The structural similarity to d-Ala-d-Ala and the detection of both axial and equatorial forms could explain its potential as a penicillin core and its capability as an antibiotic.

Quantum chemistry meets high-resolution spectroscopy for characterizing the molecular bricks of life in the gas-phase

Computation of accurate geometrical structures and spectroscopic properties of large flexible molecules in the gas-phase is tackled at an affordable cost using a general exploration/exploitation strategy. The most distinctive feature of the approach is the careful selection of different quantum chemical models for energies, geometries and vibrational frequencies with the aim of maximizing the accuracy of the overall description while retaining a reasonable cost for all the steps. In particular, a composite wave-function method is used for energies, whereas a double-hybrid functional (with the addition of core-valence correlation) is employed for geometries and harmonic frequencies and a cheaper hybrid functional for anharmonic contributions. A thorough benchmark based on a wide range of prototypical molecular bricks of life shows that the proposed strategy is close to the accuracy of state-of-the-art composite wave-function methods, and is applicable to much larger systems. A freely available web-utility post-processes the geometries optimized by standard electronic structure codes paving the way toward the accurate yet not prohibitively expensive study of medium- to large-sized molecules by experimentally-oriented researchers.

Promiscuity and Quantitative Contribution of UGT2B17 in Drug and Steroid Metabolism Determined by Experimental and Computational Approaches

Uridine 5'-diphospho-glulcuronosyltransferase 2B17 (UGT2B17) is important in the metabolism of steroids and orally administered drugs due to its high interindividual variability. However, the structural basis governing the substrate selectivity or inhibition of UGT2B17 remains poorly understood. This study investigated 76 FDA-approved drugs and 20 steroids known to undergo glucuronidation for their metabolism by UGT2B17. Specifically, we assessed the substrate selectivity for UGT2B17 over other UGT enzymes using recombinant human UGT2B17 (rUGT2B17), human intestinal microsomes, and human liver microsomes. The quantitative contribution of intestinal UGT2B17 in the glucuronidation of these compounds was characterized using intestinal microsomes isolated from UGT2B17 expressors and nonexpressors. In addition, a structure-based pharmacophore model for UGT2B17 substrates was built and validated using the studied pool of substrates and nonsubstrates. The results show that UGT2B17 could metabolize 23 out of 96 compounds from various chemical classes, including alcohols and carboxylic acids, particularly in the intestine. Interestingly, amines were less susceptible to UGT2B17 metabolism, though they could inhibit the enzyme. Three main pharmacophoric features of UGT2B17 substrates include (1) the presence of an accessible -OH or -COOH group near His35 residue, (2) a hydrophobic functional group at ∼4.5-5 Å from feature 1, and (3) an aromatic ring ∼5-7 Å from feature 2. Most of the studied compounds inhibited UGT2B17 activity irrespective of their substrate potential, indicating the possibility of multiple mechanisms. These data suggest that UGT2B17 is promiscuous in substrate selectivity and inhibition and has a high potential to produce significant variability in the absorption and disposition of orally administered drugs.

Steroid Hormone Androsterone Observed in the Gas Phase by Rotational Spectroscopy

We report the investigation of the steroid hormone androsterone in the gas phase. Androsterone is a male sex steroid hormone, being the first steroid hormone from this category isolated and discovered 90 years ago. Despite the chemical compositions of steroids being well-known since long ago, studying their structures in the gas phase is still a challenging task, and to date, just a handful of detailed experimental structures for steroids have been reported. The rotational spectrum of androsterone was recorded in the 2-8 GHz frequency region with a broadband chirped-pulse Fourier transform microwave spectrometer coupled with supersonic expansion. From the weak rotational spectrum, one conformer has been detected in the isolated and cold conditions of the molecular jet. The combination of the experimental results with quantum chemical calculations allowed us to unambiguously identify the conformation of androsterone in the gas phase.

A solvent-mediated conformational switch in sulfanilamide

Sulfanilamide, a widely used antibacterial drug, has been brought into the gas phase using laser ablation techniques, and its structure has been characterized in the isolated conditions of a supersonic expansion using Fourier transform microwave techniques. A single conformer stabilized by an N-H⋯OS intramolecular interaction in an equatorial disposition has been unequivocally characterized. To emulate the microsolvation process, we studied its hydrated cluster. The results show that a single water molecule alters the conformational preference and forces sulfanilamide to switch from its initial eclipsed configuration to a staggered disposition. The observed hydrated cluster adopts a structure in which water forms three hydrogen bonds with sulfanilamide stabilizing the molecule.

VDR mediated HSD3B1 to regulate lipid metabolism and promoted testosterone synthesis in mouse Leydig cells

BACKGROUND

The vitamin D receptor (VDR) mediates the pleiotropic biological actions that include osteoporosis, immune responses and androgen synthesis wherein the VDR transcriptionally regulates expression of the genes involved in this complex process. 3β-Hydroxysteroid dehydrogenase-1 (HSD3B1) is an absolutely necessary enzyme for androgen synthesis.

OBJECTIVE

The purpose of the present study was to explore the molecular mechanism of VDR mediated HSD3B1 regulation of lipid metabolism and testosterone synthesis.

METHODS

The levels of VDR, HSD3B1 and lipid metabolism associated protein were determined by quantitative real-time polymerase chain reaction (RT-qPCR) or western blot. The levels of testosterone concentrations in cell culture media serum by enzyme-linked immunosorbent assay (ELISA). Targeted relationship between VDR and Hsd3b1 was evaluated by dual-luciferase reporter assay.

RESULTS

Based on the data analysis of mouse testicular proteome, we found that the expression of HSD3B1 was significantly reduced after VDR deletion. Here, we identified that Hsd3b1 was widely expressed in different tissues of mice by RT-qPCR, and was highly expressed in testis, and mainly located in testicular Leydig cells. Dual-luciferase assay confirmed that VDR could bind candidate vitamin D responsive elements (VDREs) in upstream region of Hsd3b1, and enhance gene expression. Furthermore, over-expression VDR and HSD3B1 significantly increased testosterone synthesis in mice Leydig cells. Meanwhile, Lpl expression was significantly down-regulated and Angptl4 expression was significantly up-regulated in the present of HSD3B1 overexpression. Both LPL and ANGPTL4 play important roles in regulating lipid metabolism.

CONCLUSIONS

The present study unveiled VDR mediated HSD3B1 to regulate lipid metabolism and promoted testosterone synthesis in mouse Leydig cells. These findings will greatly help us to understand the roles of VDR and HSD3B1 in testosterone synthesis and lipid metabolism.

Unexpected discovery of estrone in the rotational spectrum of estradiol: a systematic investigation of a CP-FTMW spectrum

We report the reinvestigation of the high-resolution rotational spectrum of estradiol. After removing the known spectral lines corresponding to three conformers of estradiol identified in the gas phase before, a large number of spectral lines remained unassigned in the spectrum. The observation of remaining lines is a common feature in spectra obtained by broadband rotational spectroscopy. In our reinvestigation, the detection of certain patterns resulted in two new sets of experimental rotational constants. Here we describe a systematic analysis, which together with quantum-chemical computations culminated in the assignment of two estrone conformers, namely exhibiting the trans- and the cis-arrangement of the hydroxy group attached to the rigid steroid backbone. Estrone and estradiol only differ in two atomic mass units, and they show a dynamic interconversion equilibrium under certain conditions, which might also have been the case in our experiments due to the heating temperature of 195 °C. The results illustrate the potential of high-resolution rotational spectroscopy to discern between structurally related molecules and to provide their gas-phase structures without information beforehand exploiting the benefit of having remaining unassigned rotational transitions in the spectrum.

Radical-Radical Reaction Dynamics Probed Using Millimeterwave Spectroscopy: Propargyl + NH2/ND2

We apply chirped-pulse uniform flow millimeterwave (CPUF-mmW) spectroscopy to study the complex multichannel reaction dynamics in the reaction between the propargyl and amino radicals (C₃H₃ + NH₂/ND₂), a radical-radical reaction of importance in the gas-phase chemistry of astrochemical environments and combustion systems. The photolytically generated radicals are allowed to react in a well-characterized quasi-uniform supersonic flow, and mmW rotational spectroscopy (70-93 GHz) is used for simultaneous detection of the reaction products: HCN, HNC, HC₃N, DCN, DNC, and DC₃N, while spectral intensities of the measured pure-rotational lines allow product branching to be quantified. High-level electronic structure calculations were used for theoretical prediction of the reaction pathways and branching. Experimentally deduced product branching fractions were compared with the results from statistical simulations based on the RRKM theory. Product branching was found to be strongly dependent on the excess internal energy of the C₃H₃ and NH₂/ND₂ reactants.

Understanding the abundance of the rare sugar β-D-allose

The conformational landscape of β-D-allose, a rare sugar, has been investigated using laser ablation in combination with high-resolution rotational spectroscopy. Altogether, three species are identified, exhibiting a counter-clockwise intramolecular hydrogen...