Jaroslav Pecka

Solid phase synthesis of glycopeptide dendrimers with Tn antigenic structure and their biological activities. Part I

Multiple antigenic peptides containing dimeric Tn antigen [Ac‐(Tn)2‐γ‐Abu]4‐(Lys‐X)2‐Lys‐β‐Ala (V: X=0; VIII: X=γ‐Abu) and [Ac‐(Tn)2‐γ‐Abu]8‐(Lys‐X)4‐(Lys‐X)2‐Lys‐β‐Ala (XI: X=0; XIV: X=γ‐Abu), immobilized on biocompatible Tenta Gel S NH2 support were prepared by SPPS. Rosetting tests of V, VIII, XI and XIV showed positive reactions with anti‐Tn (DAKO) and Tn+ erythrocytes, with anti‐Tn/A (BRIC 66) and Tn+ and A erythrocytes, other combinations were negative. In all the animals immunized with XIV, we found a remarkable increase in the level of anti‐Tn (titre 2000–64 000, score 105–167) and no change of anti‐A levels (titre 8, score 13–17). Neither non‐immune nor immune sera showed any reactivity with T+, Cad+ and blood group O erythrocytes. Immunized mice did not exhibit any sign of adverse reaction to the administered conjugates. Biological activities were correlated with molecular modelling and molecular dynamic calculations. The biological activities of these synthetic Tn antigen conjugates (good availability for the immunological interactions, highly specific immunogenicity, good biological tolerance) together with their precise chemical characterization seem to be a promising approach to preparation of anti‐tumour vaccine and affinity purification of anti‐Tn antibodies. Copyright

Simple analytical method for evaluation of statistical importance of correlations in QSAR studies

A new general method allowing to evaluate the statistical importance of independent correlations from multilinear QSAR models was proposed. The method is applicable to any multilinear QSAR model involving N experimental points and M independent parameters. The application of this new method is demonstrated on several examples.

Similarity approach to chemical reactivity. Theoretical justification of the Hammond postulate

The recently proposed similarity index was applied to the quantitative justification of the empirical Hammond postulate for a series of selected pericyclic reactions. In keeping with the expectations of the postulate the transition states were shown to be reactant-like for exothermic and product-like for endothermic reactions.

Synthesis of a Covalent Square Grid

For quite a few years, the area of atomic and molecular scale technology has been the subject of intense speculation.1,2 There has also been considerable interest in the actual synthesis of various more or less complex single-molecule devices, both electrical3 (e.g. switches4 and wires5) and mechanical (e.g., brakes,6 turnstiles,7 levers,8 and even a mousetrap9). However, it is often not very clear how any of these devices would be used in practice when they float about freely in a solution. Some degree of control over their location in space and absolute orientation would appear highly desirable, particularly if several devices are to work together. One possibility is to adsorb them on a surface in an oriented fashion, perhaps singly for work with an STM tip10 or in a periodic array dictated by a surface lattice,11 or attached to the outside of a self-assembled monolayer. Still, the degree of control over their location in space and absolute orientation would remain rather limited. Another possibility is to allow the devices to form a three-dimensionally periodic lattice of a crystal. Usually, they will then be packed in a manner over which one has limited control, if any. Such regular arrays could still be quite useful, e.g., as quantum dots, if one had complete control over the separations, the nature of the material that separates them, and the geometry of the lattice. Much progress in crystal engineering has been made by numerous research groups, and this type of control may be available in the future.

Polarographic Reduction of Aldehydes and Ketones. V. Reduction Course of Some β-Ketosulphides and Effects of Alkyl Groups on Sulphur

β-Ketosulphides of the type C6H5COCH2CH(C6H5)SR are reduced at the carbonyl group. The protonized carbonyl group is reduced in two one-electron steps, the unprotonized form in one two-electron process, which differs from the reduction of corresponding β-aminoketones. The effects of alkyl groups at sulphur and nitrogen on the reduction of the carbonyl group are compared.