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169(1-3) (2000), 287-293
beta-glucosidase (beta-GLS) layers of the enzyme, each separated by oppositely charged polyelectrolyte (poly(styrenesulfonate), PSS), were deposited onto polystyrene (PS) latex particles using the layer-by-layer adsorption technique. Electrophoretic mobility (EPM) and single-particle light scattering (SPLS) measurements revealed regular and step- wise assembly of beta-GLS/PSS multilayers on the colloidal particles. Alternating positive and negative zeta-potentials were observed for beta-GLS and PSS deposition, respectively. An average thickness of 3.5 +/- 0.6 nm was calculated for each beta-GLS/PSS layer pair from SPLS data. The immobilized catalyst (in the form of an enzyme multilayer film on particles) proved to be active in the glucosidation of dodecanol, yielding dodecyl-beta-D-glucopyranoside. The product yield increased with increasing enzyme layer number for beta- GLS multilayer-coated PS particles when the outermost layer was polyelectrolyte. (C) 2000 Elsevier Science B.V. All rights reserved.

[59] Assembly and Structural Study of the Films of Immunoglobulin-M on Solid Substrates

R. L. Kayushina, A. L. Tolstikhina, N. D. Stepina, V. V. Belyaev, V. A. Lapuk and E. Y. Varlamova

Crystallogr. Rep. 45(6) (2000), 1001-1006

Immunoglobulin M (IgM) was immobilized from a solution by the method of charge self-assembly on solid substrates (ordered polyelectrolytes and as-cleaved mica). The process of film formation and the structural organization was controlled and studied by the methods of atomic-force microscopy and X-ray reflectometry. It was shown that adsorption from rather concentrated (0.680-0.068 mg/ml) IgM solutions gave rise to formation of 100- to 150-Angstrom -thick continuous protein layers. At lower concentrations (0.006 mg/ml), no continuous protein films were formed. The substrates of mica-type atomically smooth surfaces provide a higher image resolution, which, in turn, allows the observation of isolated IgM molecules and their aggregates. In the image plane, the molecules have rounded contours 300-500 Angstrom in diameter and 40-60 Angstrom in height. (C) 2000 MAIK ''Nauka/ Interperiodica''.

[60] Layer-by-Layer Electrostatic Deposition of Biomolecules on Surfaces for Molecular Recognition, Redox Mediation and Signal Generation

E. J. Calvo, F. Battaglini, C. Danilowicz, A. Wolosiuk and M. Otero

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