Modified blood group A trisaccharide probes: synthesis and interaction with antibodies

Three derivatives modified at the acetamide fragment of blood group trisaccharide A, GalNAcalpha1-3(Fucalpha1-2)Galbeta-O-spacer were synthesised. In the first compound the amide oxygen was substituted for the sulfur atom. In the second compound the methyl group was replaced with the trifluoromethyl moiety, and in the third compound the methyl group was replaced with the hydrogen atom. The interaction of these probes with anti-A monoclonal antibodies gives the information about significance of trisaccharide methyl and carbonyl groups for the formation of protein-carbohydrates complex.     

Planar defects in Mo2BC. An electron microscope study

Structural relationships between Mo₂BC, σ-MoB, β-MoB, and β-MoC_1?x are described and possibilities for planar intergrowth defects (Wadsley defects) and nonstoichiometry are considered. The term chemical stacking fault is proposed. Electron microscopy of Mo₂BC specimens revealed crystals that were rich in planar defects with widths consistent with the defects postulated.     

Artificial antigens and affinity sorbents with groups specificities Lea,Leb, and Led

Oligosaccharides of the Lewis system have been synthesized in the form of 3-aminopropylglycosides, from which neoglycoproteins and affinity sorbents have been obtained. All three oligosaccharides were obtained from one and the same precursor.     

Structure of 3-chloromethyl-3-oxo-2H-1,4, 3-benzoxa2aphosphorine

The six-membered heterocycle in the compressed bicyclic structure of 3-chloromethyl-3-oxo-2H-1,4,3-benzoxazaphosphorine has distorted C² -sofa conformation with a gauche C1-C-P=O fragment. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2357–2359, October, 1989.     

Synthesis of alkyl- and aryl(o-oxyphenoxymethyl) phosphinic acids

Conclusions Cleavage of 2-oxo-2-chloromethyl-1,3,2-benzodioxaphosphole by Grignard reagents produced pyrocatechol esters of alkyl- and aryl(chloromethyl)phosphinic acids, cyclization of which and subsequent hydrolysis lead to alkyl- and aryl(o-oxyphenoxymethyl)phosphinic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 943–946, April, 1989.     

ELECTROSTATIC EFFECTS IN THE PHOTOREDUCTION OF FLAVINS BY EDTA

The anaerobic photoreduction of riboflavin, flavin mononucleotide, N(3)-carboxymethylriboflavin, N(3)-methyl-lumiflavin, and lumiflavin by EDTA was studied in aqueous solution over the pH range 2.5–10. The electrostatic effects of the electron donor-acceptor pair produce a secondary effect on the reactivity, and this effect can be predicted from the product of the charges (Z_D x Z_A). The trianonic and tetraanonic species of EDTA have nitrogens which are free from intramolecular hydrogen bonding, and these species are potentially the most reactive. However, in some pH regions the electrostatic effect can become the dominant factor when both the electron donor and acceptor become negatively charged. The excited states of flavins are susceptible to charge effects whether the charge is localized on the side chain or involves the isoalloxazine ring system.     

Crystal structure of the benzene disolvate of the cis isomer of the 2-chloromethyl-2-phenyl-1,3,2-benzoxazaphosphole dimer

The x-ray crystal and molecular structure of the benzene disolvate of the soluble diastereomer of the 2-chloromethyl-2-phenyl-1,3,2-benzoxazaphosphole dimer is solved. This diastereomer is the cis isomer.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2313–2316, October, 1991.     

Structure of 2-chloromethyl-2-oxo-3H-1,4,2-benzoxazaphosphorine

The compressed bicyclic structure of 2-chloromethyl-2-oxo-3H-1,4,2-benzoxaza-phosphorine features a sixmembered heterocycle with P ²,C³ -half-chair with axial equatorial orientation of the P=O group and axial orientation of the CH₂Clgroup. Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2355–2357, October, 1989.