Ribosome kinetics and aa-tRNA competition determine rate and fidelity of peptide synthesis

It is generally accepted that the translation rate depends on the availability of cognate aa-tRNAs. In this study it is shown that the key factor that determines translation rate is the competition between near-cognate and cognate aa-tRNAs. The transport mechanism in the cytoplasm is diffusion, thus the competition between cognate, near-cognate and non-cognate aa-tRNAs to bind to the ribosome is a stochastic process. Two competition measures are introduced; C(i) and R(i) (i = 1, 64) are quotients of the arrival frequencies of near-cognates vs. cognates and non-cognates vs. cognates, respectively. Furthermore, the reaction rates of bound cognates differ from those of bound near-cognates. If a near-cognate aa-tRNA binds to the A site of the ribosome, it may be rejected at the anti-codon recognition step or proofreading step or it may be accepted. Regardless of its fate, the near-cognates and non-cognates have caused delays of varying duration to the observed rate of translation. Rate constants have been measured at a temperature of 20 °C by (Gromadski, K.B., Rodnina, M.V., 2004. Kinetic determinants of high-fidelity tRNA discrimination on the ribosome. Mol. Cell 13, 191–200). These rate constants have been re-evaluated at 37 °C, using experimental data at 24.5 °C and 37 °C (Varenne, S., et al., 1984. Translation in a non-uniform process: effect of tRNA availability on the rate of elongation of nascent polypeptide chains. J. Mol. Biol. 180, 549–576). The key results of the study are: (i) the average time (at 37 °C) to add an amino acid, as defined by the ith codon, to the nascent peptide chain is: τ(i) = 9.06 + 1.445 × [10.48C(i) + 0.5R(i)] (in ms); (ii) the misreading frequency is directly proportional to the near-cognate competition, E(i) = 0.0009C(i); (iii) the competition from near-cognates, and not the availability of cognate aa-tRNAs, is the most important factor that determines the translation rate – the four codons with highest near-cognate competition (in the case of E. coli) are [GCC] > [CGG] > [AGG] > [GGA], which overlap only partially with the rarest codons: [AGG] < [CCA] < [GCC] < [CAC]; (iv) based on the kinetic rates at 37 °C, the average time to insert a cognate amino acid is 9.06 ms and the average delay to process a near-cognate aa-tRNA is 10.45 ms and (vii) the model also provides estimates of the vacancy times of the A site of the ribosome – an important factor in frameshifting.     

Crystalline polysilicate magadiite with intercalated n-alkylmonoamine and some correlations involving thermochemical data

Synthesized hydrated lamellar acidic crystalline magadiite (H₂Si₁₄O₂₉·2H₂O) nanocompound was used as host for intercalation of polar n-alkylmonoamine molecules of the general formula H₃C(CH₂)_nNH₂ (n = 1–6) in aqueous solution. The original interlayer distance (d) of 1500 pm, determined by X-ray powder diffraction patterns, increases after intercalation. The values correlated with the number of aliphatic amine carbon (n_c) atoms: d = [(1312 ± 11) + (21 ± 2)]n_c. The amount of intercalated amines (N_s), decreased as n_c increased: N_s = [(5.82 ± 0.04) − (0.45 ± 0.01)]n_c. The acidic layered nanocompound was calorimetrically titrated with the amines and the thermodynamic data gave exothermic values for all guest molecules, as shown by the correlation: Δ_intH = −[(24.45 ± 0.49) − (1.91 ± 0.10)]n_c and d = [(1576 ± 16) − (10.8 ± 1.0)]Δ_intH. The negative values of the Gibbs energies and the positive entropies also presented the correlations: Δ_intG = −[(22.8 ± 0.2) − (0.2 ± 0.1)]n_c and Δ_intS = [(6 ± 1) + (5 ± 1)]n_c, respectively.     

Structures of 3,3′-dicarbometoxy-2,2′-bipyridine complexes with silver(I) and copper(II) cations

The structures of 3,3′-dicarbometoxy-2,2′-bipyridine (dcmbpy) complexes with copper(II) and silver(I) cations have been determined using single crystal X-ray-diffraction. The crystals of Cu(dcmbpy)Cl₂ are monoclinic, C2/c, a = 16.966(3), b = 18.373(3), c = 13.154(2) Å, β = 126.543(3)°. The crystals of Ag(dcmbpy)NO₃ · H₂O are also monoclinic, C2/c, a = 16.7547(13), b = 11.0922(9), c = 18.7789(18) Å, β = 100.228(7)°. The results have been compared with the literature data on the complexes of dcmbpy and its precursors: 2,2′-bipyridine (bpy) and 3,3′-dicarboxy-2,2′-bipyridine (dcbpy). Two types of complexes of 3,3′-carboxy derivatives of bpy are distinguished: (1) with metal atom bonded to two N atoms of the same molecule and (2) with metal atom bonded to two N atoms of two different molecules. The Cu(dcmbpy)Cl₂ complex belongs to the first type, whereas Ag(dcmbpy)NO₃ · H₂O belongs to the second type.     

Structure analysis and the standard molar enthalpy of formation of a coordination polymer [Co(TO)2Cl2]n (TO = 1,2,4-triazole-5-one)

A coordination polymer was synthesized by the reaction of CoCl₂ with 1,2,4-triazole-5-one (TO) and charaterized by means of IR and TG–DTG. Single-crystal structure analysis showed that the complex crystallized in the monoclinic space group C2/c: a = 23.105(9) Å, b = 3.5683(2) Å, c = 13.589(6) Å,  = 90°, β = 124.038(4)°, γ = 90°, V = 928.4(7) Å³, Z = 4. The standard molar enthalpy of formation of the complex was determined to be (−1034.28 ± 0.95) kJ mol⁻¹.     

Three interpenetrated frameworks constructed by long flexible N,N′-bipyridyl and dicarboxylate ligands

Three interpenetrated polymeric networks, {[Co(bpp)(OH-BDC)] · H₂O}_n (1) [Ni(bpp)_1.5(H₂O)(OH-BDC)]_n (2) and {[Cd(bpp)(H₂O)(OH-BDC)] · 2H₂O}_n (3), have been prepared by hydrothermal reactions of 1,3-bis(4-pyridyl)propane (bpp), 5-hydroxyisophthalic acid (OH-H₂BDC), with Co(NO₃)₂ · 6H₂O, Ni(NO₃)₂ · 6H₂O and Cd(NO₃)₂ · 4H₂O, respectively. Single-crystal X-ray diffraction analyses reveal that the three compounds all exhibit interpenetrated but entirely different structures. Compound 1 is a fourfold interpenetrated adamantanoid structure with water molecules as space fillers, in which bpp adopts a TG conformation (T = trans, G = gauche). Compound 2 is an interdigitated structure from the interpenetrated long arms of one-dimensional molecular ladders, while bpp in 2 adopts both TT and TG conformations. Compound 3 is a twofold interpenetrated three-dimensional network from a one-dimensional metal-carboxylate chain bridged by TG conformational bpp. The hydrogen bonding interactions in 1–3 further stabilize the whole structural frameworks and play critical roles in their constructions.     

The molecular structure and conformation of trichloronitromethane as determined by gas-phase electron diffraction and theoretical calculations

The molecular structure of trichloronitromethane has been studied in the gas phase using electron diffraction data. The molecules are found to undergo low barrier rotation about the CN bond with a planar CNO₂ moiety in agreement with HF/MP2/B3LYP/6-311G(d,p) calculations. The experimental data are consistent with a dynamic model using a potential function for the torsion of V = (V₆/2)(1 − cos 6τ). The major geometrical parameters (r_g and ) for the eclipsed form, obtained from least squares analysis of the data are as follows: r(NO₃) = r(NO₄) = 1.213(2) Å, r(CN) = 1.592(6) Å, r(CCl)_av = 1.749(1) Å, Cl₅CN/Cl₆CN = 109. 6°/106.3°(2), O₃NC/O₄NC = 117. 6°/114.1°(4), τCl₅C₁N₂O₃ = 0.0°, and V₆ = 0.20(25) kcal/mol.     

The pseudogap in LSCO-type high-temperature superconductors as seen by neutron crystal-field spectroscopy

We studied the isotope, pressure and doping effects on the pseudogap temperature T^* by neutron spectroscopic experiments of the relaxation rate of crystal-field excitations in La_1.96−xSr_xHo_0.04CuO₄ (x = 0.11, 0.15, 0.20, 0.25) on the high-resolution time-of-flight spectrometer FOCUS at SINQ, PSI. We found clear evidence for the opening of a pseudogap in the underdoped regime at T^*(x = 0.11) = (82.2 ± 1.2) K as well as in the overdoped and the heavily overdoped compounds at T^*(x = 0.2) = (49.2 ± 0.7) K and at T^*(x = 0.25) = (46.5 ± 0.5) K, respectively. Furthermore, we investigated the effect of oxygen isotope substitution on the pseudogap, the experiments revealed ΔT^*(x = 0.11) = (21.3 ± 5.2) K and ΔT^*(x = 0.2) = (4.5 ± 1.3) K. The application of hydrostatic pressure (0.8 and 1.2 GPa) on the optimally doped compound (x = 0.15) results in a downward shift of dT^*/dp = (−5.9 ± 1.6) K/GPa.     

On the thermodynamic equilibrium between ice and electrolyte solutions in the conditions of confined geometry

For a small volume (of about 10⁻⁶ cm³) of NaCl and other electrolyte solutions (C = 0.1 and 1 M) in thin (r = 5/10 μm) single quartz capillaries, dependencies of the column length l of frozen solutions on the temperature t were measured using comparator IZA-2 in a thermostated chamber. At temperatures range t > −4 °C (for C = 0.1 M) and t > −8 °C (for C = 1 M) the l(t) dependencies are reversible and therefore correspond to establishment of an equilibrium between ice-1 and the solution.

From the constants mass condition of the dissolved salt in a frozen column, the l(t) expression was derived, which includes thermodynamic relation between solution concentration in an equilibrium with ice, C_s, and the temperature t for bulk systems. Deviations from the data known for bulk solutions were observed in thin capillaries when temperature t decreased to −3 °C (for 0.1 M NaCl) and to −6 °C for 1 M NaCl solution.

This effect may be a result of strong adhesion of the ice column to capillary walls. In this case, some internal stresses arise in frozen solution resulting in a deviation from thermodynamic equilibrium conditions for bulk systems. When approaching the temperature of ice melting, adhesion forces decrease due to formation of a thin non-freezing water interlayer on the capillary wall. In this temperature range the experimental data are in agreement with the predictions for bulk systems. It was supposed that the observed deviation in thin capillaries may be caused by formation of an amorphous ice phase with higher density as compared with the ice-1 during rapid freezing, or by an effect of ice microlenses formation. Both effects will result in a deviation from the phase diagram corresponding to a bulk solution.     

Determination of cilnidipine, a new calcium antagonist, in human plasma using high performance liquid chromatography with tandem mass spectrometric detection

A rapid, sensitive and reliable high performance liquid chromatographic method coupled with tandem mass spectrometry (HPLC–MS/MS) has been developed and validated for the determination of cilnidipine, a relatively new calcium antagonist, in human plasma. The reversed-phase chromatographic system was interfaced with a TurboIonSpray (TIS) source. Nimodipine was employed as the internal standard (IS). Sample extracts following protein precipitation were injected into the HPLC–MS/MS system. The analyte and IS were eluted isocratically on a C18 column, with a mobile phase consisting of CH₃OH and NH₄Ac (96:4, v/v). The ions were detected by a triple quadrupole mass spectrometric detector in the negative mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions m/z 491.2 → 122.1 and m/z 417.1 → 122.1 for cilnidipine and for the IS, respectively. The analysis time for each run was 3.0 min. The calibration curve fitted well over the concentration range of 0.1–10 ng mL⁻¹, with the regression equation Y = (0.103 ± 0.002)X + (0.014 ± 0.003) (n = 5), r = 0.9994. The intra-day and inter-day R.S.D.% were less than 12.51% at all concentration levels within the calibration range. The recoveries were between 92.71% and 97.64%. The long-term stability and freeze-thaw stability were satisfying at each level. The present method provides a modern, rapid and robust tool for pharmacokinetic studies of cilnidipine.     

Refined heat capacity of LaPO4 in the temperature range 0–1600 K

In the present work temperature dependence of heat capacity of cesium tantalum tungsten oxide has been measured first in the range from 7 to 350 K and then between 330 and 630 K, respectively, by precision adiabatic vacuum and dynamic calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity C_p° (T), enthalpy H°(T) − H°(0), entropy S°(T) − S°(0) and Gibbs function G°(T) − H°(0), for the range from T → 0 to 630 K. The structure of CsTaWO₆ is refined by the Rietveld method: space group F d3m, Z = 8, a = 10.3793(2) Å, V = 1118.14(4) Å³. The high-temperature X-ray diffraction was used for the determination of temperature of phase transition and coefficient of thermal expansion.     

Theoretical study on the intramolecular proton transfer reactions of 3-methyl-5-hydroxyisoxazole and its water complexes

The optimized structures and proton transfer reactions of 3-methyl-5-hydroxyisoxazole and its water complexes (3-M-5-HIO · (H₂O)_n · (n = 0–3)) were computed at B3LYP and MP2 theoretical level. The results indicates that 3-M-5-HIO has four isomers (Ecis, Etrans, K1 and K2), and the keto tautomer, and K2 is the most stable isomer in the gas phase. Hydrogen bonding between 3-M-5-HIO and the water molecules can dramatically lower the barrier by the concerted transfer mechanism. Ecis · (H₂O)₃ → K1 · (H₂O)₃ and Ecis · (H₂O)₂ → K2 · (H₂O)₂ is found to be very efficient. Comparing with the proton transfer mechanism of 5-HIO shows that the methyl substitution prevents the intramolecular proton transfer.     

Synthesis, structure and oxygen nonstoichiometry of La0.4Sr0.6Co1−yFeyO3−δ

The samples of La_0.4Sr_0.6Co_1−yFe_yO_3−δ (y = 0.2 and 0.4) were prepared using both conventional ceramic technique and nitrate–citrate precursors technique. The phase identification was made by X-ray diffraction method. The refinement of structural parameters from the XRD and neutron diffraction measurements was performed by full profile Rietveld analysis. Neutron diffraction showed that both samples possess distorted perovskite-type structure. Oxygen nonstoichiometry was measured by chemical analysis and thermogravimetry (TG) analysis in the range 20 ≤ T/°C ≤ 900 and 2E-5 ≤ pO₂/atm ≤ 4E-1. TG-experiments indicate a relatively fast and reversible oxygen exchange at pO₂ > 1E-2 atm. Mass saturation occurs at T < 300 °C upon cooling. The absolute value of oxygen nonstoichiometry was determined by iodometric titration measurements. It was found that both samples have practically stoichiometric composition at 300 °C in air and δ increases with increasing temperature and decreasing oxygen partial pressure.     

QTAIM study of the closed-shell interactions in peptide secondary structures: A cluster treatment of oligo- and polyalanines

The closed-shell interactions in oligo- and polyalanines are studied by the quantum theory of atoms in molecules (QTAIM) using electron densities derived from the B3LYP/6-31+G^** ground-state electronic wave-functions. The QTAIM enabled us to identify a large number of the intraturn closed-shell stabilizing interactions in the β-turns, which were presented by several conformers of the tetrapeptide model compound. We found that only β-turn type IVa exhibits a 10-member pseudocycle. The intrachain H-bonds between the adjacent N–H and CO groups in the antiparallel β-sheet conformation of polyalanine have not been found. At the same time, these interactions do exist in the parallel conformation and are even stronger than the interchain N–H…O bonds. A weak interaction between the CO group at the position i and the side-chain C–H group at the position i + 3 was detected in the -helical conformation of polyalanine.     

The efficacy of nitrosonaphthol functionalized XAD-16 resin for the preconcentration/sorption of Ni(II) and Cu(II) ions

Amberlite XAD-16 resin has been functionalized using nitrosonaphthol as a ligand and characterized employing elemental, thermogravimetric analysis and FT-IR spectroscopy. The sorption of Ni(II) and Cu(II) ions onto this functionalized resin is investigated and optimized with respect to the sorptive medium (pH), shaking speed and equilibration time between liquid and solid phases. The monitoring of the influence of diverse ions on the sorption of metal ions has revealed that phosphate, bicarbonate and citrate reduce the sorption up to 10–14%. The sorption data followed Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherms. The Freundlich parameters computed are 1/n = 0.56 ± 0.03 and 0.49 ± 0.05, A = 9.54 ± 1.5 and 6.0 ± 0.5 mmol g⁻¹ for Ni(II) and Cu(II) ions, respectively. D–R isotherm yields the values of X_m = 0.87 ± 0.07 and 0.35 ± 0.05 mmol g⁻¹ and of E = 9.5 ± 0.23 and 12.3 ± 0.6 kJ mol⁻¹ for Ni(II) and Cu(II) ions, respectively. Langmuir characteristic constants estimated are Q = 0.082 ± 0.005 and 0.063 ± 0.003 mmol g⁻¹, b = (4.7 ± 0.2) × 10⁴ and (7.31 ± 0.11) × 10⁴ l mol⁻¹ for Ni(II) and Cu(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantities of ΔH = −58.9 ± 0.12 and −40.38 ± 0.11 kJ mol⁻¹, ΔS = −183 ± 10 and −130 ± 8 J mol⁻¹ K⁻¹ and ΔG = −4.4 ± 0.09 and −2.06 ± 0.08 kJ mol⁻¹ at 298 K for Ni(II) and Cu(II) ions, respectively. Using kinetic equations, values of intraparticle transport and of first order rate constant have been computed for both the metal ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination in tea, vegetable oil, hydrogenated oil (ghee) and palm oil by atomic absorption spectrometry using direct and standard addition methods.     

Hydrothermal synthesis and intercalation behavior of a layered titanium phosphate Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16, with an extended γ-phase intercalated into organic amine

With a hydrothermal technique, a layered titanium phosphate with the formula Ti₂(H₂PO₄)(HPO₄)(PO₄)₂ · 0.5C₆N₂H₁₆ (denoted TP-J2) has been prepared by treating the Ti/H₃PO₄/H₂O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state ³¹P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å.  = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip.     

Langmuir monolayer properties of the fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC)

Surface pressure–area (π–A), surface potential–area (ΔV–A), and dipole moment–area (μ–A) isotherms were obtained for the Langmuir monolayer of two fluorinated-hydrogenated hybrid amphiphiles (sodium phenyl 1-[(4-perfluorohexyl)-phenyl]-1-hexylphosphate (F6PH5PPhNa) and (sodium phenyl 1-[(4-perfluorooctyl)-phenyl]-1-hexylphosphate (F8PH5PPhNa)), DPPC and their two-component systems at the air/water interface. Monolayers spread on 0.02 M Tris buffer solution (pH 7.4) with 0.13 M NaCl at 298.2 K were investigated by the Wilhelmy method, ionizing electrode method and fluorescence microscopy. Moreover, the miscibility of two components was examined by plotting the variation of the molecular area and the surface potential as a function of the molar fraction for the fluorinated-hydrogenated hybrid amphiphiles on the basis of the additivity rule. The miscibility of the monlayers was also examined by construction of two-dimensional phase diagrams. Furthermore, assuming the regular surface mixture, the Joos equation for analysis of the collapse pressure of two-component monolayers allowed calculation of the interaction parameter (ξ) and the interaction energy (−Δ) between the fluorinated-hydrogenated hybrid amphiphiles and DPPC. The observations by a fluorescence microscopy also supported our interpretation as for the miscibility in the monolayer state. Comparing the monolayer behavior between the two binary systems, no remarkable difference was found among various aspects. Among the two combinations, the mole fraction dependence in monlayer properties was commonly classified into two ranges: 0 ≤ X ≤ 0.3 and 0.3 < X ≤ 1. Dependence of the chain length of fluorinated part was reflected for the molecular packing and surface potential.     

Interaction of sodium cholate with dioctadecyldimethylammonium chloride vesicles in aqueous dispersion

Mixtures of dioctadecyldimethylammonium chloride (DODAC) cationic vesicle dispersions with aqueous micelle solutions of the anionic sodium cholate (NaC) were investigated by differential scanning calorimetry, DSC, turbidity and light scattering. Within the concentration range investigated (constant 1.0 mM DODAC and varying NaC concentration up to 4 mM), vesicle → micelle → aggregate transitions were observed. The turbidity of DODAC/NaC/water depends on time and NaC/DODAB molar concentration ratio R. At equilibrium, turbidity initially decreases smoothly with R to a low value (owing to the vesicle–micelle transition) when R = 0.5–0.8 and then increases steeply to a high value (owing to the micelle–aggregate transition) when R = 0.9–1.0. DSC thermograms exhibit a single and sharp endothermic peak at T_m ≈ 49 °C, characteristic of the melting temperature of neat DODAC vesicles in water. Upon addition of NaC, T_m initially decreases to vanish around R = 0.5, and the main transition peak broadens as R increases. For R > 1.0 two new (endo- and exothermic) peaks appear at lower temperatures indicating the formation of large aggregates since the dispersion is turbid. All samples are non-birefringent. Dynamic light scattering (DLS) data indicate that both DODAC and DODAC/NaC dispersions are highly polydisperse, and that the mean size of the aggregates tends to decrease as R increases.     

Kinetics study of the gas-phase reactions of C2F5OC(O)H and n-C3F7OC(O)H with OH radicals at 253–328 K

The rate constants, k₁ and k₂ for the reactions of C₂F₅OC(O)H and n-C₃F₇OC(O)H with OH radicals were measured using an FT-IR technique at 253–328 K. k₁ and k₂ were determined as (9.24 ± 1.33) × 10⁻¹³ exp[−(1230 ± 40)/T] and (1.41 ± 0.26) × 10⁻¹² exp[−(1260 ± 50)/T] cm³ molecule⁻¹ s⁻¹. The random errors reported are ±2 σ, and potential systematic errors of 10% could add to the k₁ and k₂. The atmospheric lifetimes of C₂F₅OC(O)H and n-C₃F₇OC(O)H with respect to reaction with OH radicals were estimated at 3.6 and 2.6 years, respectively.     

The potential energy function for the ground state of CCl calculated from spectroscopic data

The dissociation energy (D_e= 57754±872 cm⁻¹ has been estimated for the ground state of CCl⁺ by fitting a Hulburt-Hirschfelder potential to the RKR turning points. This value of D_e has been used together with molecular constants B_e, ω_e, a_i (i= 1–6) and R_e obtained by Gruebele and co-workers to construct a potential energy function for CCl⁺ in the form of a perturbed Morse oscillator.     

Comparative characteristics of texture and properties of hybrid organic–inorganic adsorbents functionalized by amine and thiol groups

The structure and texture characteristics of the hybrid organic–inorganic adsorbents, which were obtained by using of two-component systems of “structure-forming agent/trifunctional silane”, are compared as follows: the first component is Si(OC₂H₅)₄ or (C₂H₅O)₃Si–A–Si(OC₂H₅)₃, where A = –(CH₂)₂– or –C₆H₄–; the second one is alkoxysilane with amine (–NH₂, NH, –NH(CH₂)₂NH₂) and thiol (–SH) groups. The adsorbents, derived from TEOS, have more accessible functional groups (2.6–4.2 mmol/g) than xerogels, which are based on bis(triethoxysilanes) (1.0–2.6 mmol/g). On another hand xerogels derived from bis(triethoxysilanes) have a more extended porous structure (S_sp =516–968 m²/g, V_s = 0.418–1.490 cm³/g, d = 2.5–15.0 nm) than those that are based on TEOS (S_sp = 4–631 m²/g, V_s = 0.005–1.382 cm³/g, d = 2.3–17.7 nm). The geometric dimensions of functional groups have a more essential effect on the parameters of porous structure in the case of TEOS-derived xerogels. Using solid-state NMR spectroscopy, it has been shown that in synthesis of xerogels with the use of TEOS, the molecular frame of globules is formed by structural units Qⁿ (n = 2,3,4), and the functional groups exist as structural units of Tⁿ (n = 2,3). The xerogels obtained with using bis(triethoxysilanes) consist only of structural units of Tⁿ-type (n = 1,2,3).