The rotational spectrum of the weakly bound Kr-CO molecular complex formed in a pulsed molecular jet has been measured in the frequency range 112–150 GHz on an intracavity orotron-based spectrometer. The measured b-type transitions include the R branch of the band K = 1-0 with the rotational numbers J from 16 to 25 and the P branch of the band K = 2-1 with the rotational numbers J from 13 to 17. For the K = 1-0 band, we succeeded in recording transitions in complexes that consist of all stable Kr isotopes, i.e., 84Kr-CO, 86Kr-CO, 82Kr-CO, 83Kr-CO, and 80Kr-CO. For the K = 2-1 band, we observed transitions in the two most abundant isotopologues, 84Kr-CO and 86Kr-CO. The obtained data were used to determine the rotational and centrifugal constants of the Kr-CO complex.

The structure of the M1 protein of the influenza virus A/Puerto Rico/8/34 (PR8, subtype H1N1) in solution at acidic pH and in the composition of the virion has been studied by the tritium planigraphy method. A model of the spatial structure was constructed using a special algorithm simulating the experiment and a set of algorithms for predicting the secondary structure and disordered regions in proteins. The tertiary structure was refined using the Rosetta program. For a comparison of the structures in solution and inside the virion, the data of X-ray diffraction analysis for the NM domain were also used. The main difference in the structures of the protein in solution and the crystalline state is observed in the region of contact of N and M domains, which in the crystalline state is packed more densely. The regions of the maximum label incorporation almost completely coincide with unstructured regions in the protein that were predicted by the bioinformatics analysis. These regions are concentrated in the C domain and in loop regions between M, N, and C domains. The data were confirmed by analytical centrifugation and dynamic light scattering. Anomalous hydrodynamic dimensions and a low structuration of the M1 protein in solution were found. The polyfunctionality of the protein in the cell is probably related to its flexible tertiary structure, which, owing to unstructured regions, provides contact with various partner molecules.

The rotational spectrum of the van der Waals NH 3 -N 2 complex is studied in the frequency range of 112–130 GHz. The transitions are measured in a cold molecular beam with an intracavity spectrometer based on an orotron. A total of six new transitions of different spin modifications of the complex are recorded. Molecular parameters of the K = 0 ground state are determined for the ortho NH 3 - ortho N 2 modification.

The tritium planigraphy method is based on the nonselective substitution of radioactive isotope tritium for hydrogen in hydrocarbon fragments of molecules by means of a chemical reaction involving hot tritium atoms. Data on the steric accessibility of the system components (macromolecules in the complex, amino acid residues, and even individual atomic groups of macromolecules) characterize the structure of the object. The method, applicable to substances in different phase states, has no restrictions on the molecular weight of the target. Tritium planigraphy, used equally successfully in both crystals and solutions, makes it possible to study fine changes in the structure. The main results of studies of the structure of nanosized biocompexes by tritium planigraphy are presented.

The pure rotational spectrum of the van der Waals complex, CH4–CO, has been measured using the intracavity OROTRON jet spectrometer in the frequency range of 116–146 GHz. The newly observed and assigned transitions belong to the R-branch with J numbers from 9 to 16 of the K = 1–0 sub-band. This series is a continuation to higher J-values of transitions correlating with the rotationless jM = 0 state (A symmetry state) of free methane observed previously at lower frequencies [C. Xia, K.A. Walker, A.R.W. Mckellar, J. Chem. Phys. 114 (2001) 4824]. Both data sets were analyzed together with known infrared and microwave transitions in order to determine the molecular parameters of the of CH4–CO complex in the A state. The observed millimeter-wave spectrum shows numerous additional transitions which very likely belong to CH4–CO composed of methane in the F (jM = 1) and E (jM = 2) symmetry states, but these have not yet been assigned.

The results of protein spatial structure modeling using the tritium planigraphy technique are presented. The knowledge of 3D structure of macromolecules is obligatory for understanding the basic mechanisms of interaction in biological systems and complex technological processes. Known limitations of the X-ray analysis (crystal state) and NMR (molecular weight) make it necessary to seek new approaches to modeling the spatial structure of proteins. Semiempirical tritium planigraphy is one of these approaches. The method is based on bombardment of the object with a beam of hot tritium atoms ( E at ≥ 0.3 eV) and computer simulation. On the example of proteins of different structural classes, we show that this integrated approach can yield a 3D model well consistent with the X-ray data. An important factor is the sequence of searching for contacts between secondary structure elements: the best fit with the native structure is achieved by assembling the elements from the N- to the C-terminus of the polypeptide chain.

A van der Waals complex that consists of a deuterium molecule in the ortho state and a carbon monoxide molecule, CO-ortho-D2, was studied in the frequency range 85–130 GHz with the help of an intracavity orotron-based spectrometer. Nine new lines, which correspond to rotational transitions and belong to the R and Q branches, were measured and identified. The positions of the rotational energy levels of CO-ortho-D2 were refined by comparative analysis of the transition frequencies measured in this work and previously reported microwave and infrared data.