Topochemical investigations of peptide systems

The basic principles of the topochemical approach to the investigation of the structure-function relation in peptide systems are formulated. This approach makes use of the new possibility of transforming natural peptides, consisting in the modification of the molecule as a whole and utilization of the resultant analogs to elucidate the boundaries of the stereoelectronic complementarity of the biologically active peptide to the corresponding receptor. In particular, on the example of depsipeptide antibiotics and their topochemical analogs the fruitfulness of using such compounds as tools in elucidating the physicochemical basis of functioning of biological membranes is shown. The topochemical principle has also been applied in preparing specific competitive inhibitors of proteolytic enzymes, whose study may shed light on the nature of the forces binding the substrate to the contact site of the corresponding enzyme.     

Synthesis,molecular and crystal structures,and characteristic features of electronic structures of salicylamide-based B,Si-containing chelates

The reaction of 4-(2-hydroxybenzoyl)-2,2,6,6-tetramethyl-2,6-disilamorpholine with BF₃Et₂O afforded (O-B)-chelate 4-[2-(difluoroboroxy)benzoyl]-2,2,6,6-tetramethyl-2,6-disilamorpholine. Treatment of the latter with BF₃Et₂O or SOCl₂ gave rise to products of the disilamorpholine ring opening, viz., (O-B) chelate 2-(difluoroboroxy)-N,N-bis(dimethylfluorosilylmethyl)benzamide or 2-(difluoroboroxy)-N, N-bis(dimethylchlorosilylmethyl)benzamide, respectively. The structures of the compounds synthesized were confirmed by X-ray diffraction analysis and ¹H, ¹³C, and ²⁹Si NMR spectroscopy. High-precision X-ray diffraction study and quantum-chemical calculations demonstrated that the coordination OSi bond is absent in the two last-mentioned compounds.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1846–1853, September, 2004.     

Investigations in the field of depsipeptides Communication 44. Mass spectrometric study of cyclodidepsipeptides-2,5-diketomorpholines

Conclusions The fragmentation of cyclodidepsipeptides during electron impact was investigated. The nature of the hydroxy and amino acid residues contained in the 2,5-diketomorpholines can be established on the basis of the mass spectra.For the preceding Communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1539–1543, September, 1966.     

Complete synthesis of serratamolide

Summary 1. A method for the separation and quantitative determination of - and -DNP derivatives of , -DABA, ornithine, and lysine has been proposed.2. A quantitative evaluation of the N N migration in four peptides of , -DABA has been carried out.3. The degree of migration in inactive polymyxin M and the DNP-peptides from a partial hydrolyzate of the inactivated antibiotic has been determined.4. The amino acid composition of the DNP peptide B1 from a partial hydrolyzate of active DNP-polymyxin M has been established.5. The quantitative aspect of the conversion of and diketopiperazines has been studied.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 4, pp. 277–284, 1966     

Mass-spectrometer investigation of 3, 6-dialkyl-2, 5-diketopiperazines

Analysis of mass-spectra of various 2, 5-diketopiperazines gives the basic fragmentation rules for their molecular ions, and the effects of nature and positions of substituents on the process.Mass-spectrometry Laboratory of the Institute of the Chemistry of Natural Compounds.Antibiotics Chemistry Laboratory of the Institute of the Chemistry of Natural Compounds.     

Effect of Unpaired Electron in Thermochemical Description of the Dissociation Energy of Heteronuclear Diatomic Molecules

The dissociation energy of heteronuclear diatomic molecules with polar covalent bonds was calculated by the modified Pauling procedure taking into account the presence of an unpaired electron on one of the atoms.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 341–343.Original Russian Text Copyright © 2005 by Yakovlev, Ovchinnikov, Fokeeva.     

Synthesis of 3-amino-5-nitrobenzaldehyde oxime and its conversion into 3,4-bis(3-amino-5-nitrophenyl)furoxan and isomeric 3(4)-(3-amino-5-nitrophenyl)-4(3)-nitrofuroxans

The oxime of the hitherto unknown 3-amino-5-nitrobenzaldehyde was synthesized by the reaction of 3-amino-5-nitrobenzaldehyde phenylhydrazone with excess of (NH₂OH)₂·H₂SO₄. The oxime obtained was used as the starting compound for the synthesis of novel diaryl- and arylnitrofuroxans. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2232–2235, December, 1997.