L. A. Feigin

Determination of the distance between heavy-atom markers in haemoglobin and histidine decarboxylase in solution by small-angle x-ray scattering.

where Zr(s) is the intensity of scattering by the macromolecule without markers,Zs(s) is the scattering by markers and Zs(s) is the cross term; s = 4~ sin 19/x. One of the possibilities of determining the distance between heavy-atom markers is based on the separation of the term Z*(s) from experimental scattering curves. Such experiments were carried out for solutions of gramicidin S (mol. wt 1200) [2,3]. We have carried out the analysis of expression (1) in the case of small-angle X-ray scattering by proteins with heavy-atom markers in solution and estimated the relation of the existing accuracy of experiment to the minimal value of electrons in a marker from which the scattering can be still detected [4]. Also we have found the condition under which Zs(s) is much less than Zz(s) in the region of the scattering curve subsidiary maxima [4]. These conditions are responsible for NM > 4 X 10e3 N where NM and N are the numbers of

Langmuir-blodgett films of immunoglobulins as sensing elements

SummaryLangmuir-Blodgett films of a number of native proteins have been prepared and their activities confirmed. The possibility of exploiting these layers in immunosensing structures is also reported.

Structural conversions of crystallins under senile cataract, dehydration and UV-irradiation studied by X-ray diffraction

By means of X-ray diffraction analysis, structural conversions of crystallins in human lens were detected in senile cataract and upon artificial dehydration of lens tissue. In senile cataract certain characteristics of the native three-dimensional structure of gamma- and beta-crystallins are completely lost, whereas during dehydration of lens tissue a small but significant contraction of these protein molecules takes place. Upon artificial UV-irradiation of bovine crystallins destructive changes are observed, which are very similar to those in cataract.

Structure Analysis of Langmuir-Blodgett Films with Alternating Bilayers by Means of Small-Angle X-ray Scattering and Electron Diffraction

Abstract Langmuir-Blodgett films containing alternating bilayers of 4-n-octadecylphenol (ODPh) and Ba be-henate (L-B superlattices) were prepared and studied by means of small-angle X-ray scattering and electron diffraction analysis. The spacing of the L-B superlattice is 109 A, the unit cell contains one bilayer of ODPh molecules and one bilayer of Ba behenate molecules. The structural changes which occur in these L-B superlattices during the process of cross polymerization of the ODPh in layers by electron irradiation were investigated too, and show that discrete doses of radiation can cause crosslinking of the ODPh in layers without causing substantive destruction of the Ba behenate layers.

Small angle X-ray analysis of alternate-layer Langmuir—Blodgett films

Abstract Using small-angle X-ray diffraction, we demonstrate in this Letter that alternate-layer Langmuir-Blodgett films of tricosanoic acid/1-docosylamine and docosanoic acid/1-docosylamine retain their ‘as-deposited’ structure. Both of these non-centrosymmetrical bilayer structures exhibit a smaller tilting of their hydrocarbon tails than that observed for the corresponding centrosymmetric monocomponent systems. The electron-density profiles obtained for the alternate-layer systems reveal that the points of contact for the ends of the hydrocarbon chains are shifted from the centre of the unit cell and that the density maxima, corresponding to the positions of the polar head groups, possess an asymmetrical shape.

Langmuir-Blodgett Superlattices, their Structure and Methods of Production

This paper presents methods of producing multilayered Langmuir-Blodgett films (L-B superlattices). A number of films was prepared, containing bilayers of 4-octadecylphenol (ODPh) and Ba behenate, VO- phthalocyanine and BA behenate, Chr. minutissimum reaction centers and arachidic acid, and stearatic acid and Cd (or Pb) sulfide. The degree of ordering of the structures obtained was studied by means of small-angle X-ray scattering. This method permits an estimation of the spacing of the L-B superlattices. The electron density profiles of L-B films consisting of biomolecular layers of Ba behenate and ODPh were calculated. The structural changes which occur in layers of the ODPh during the process of cross polymerization by electron irradiation and also in L-B films of Cd (Pb) stearate after exposure to an H2S atmosphere were also investigated.

Polar multilayer Langmuir-Blodgett films of p-(p-octadecyloxyphenylazo) benzenesulfonamide

Abstract We have studied the temperature dependence of the pyroelectric coefficient and spacing, the temperature and frequency dependences of the dielectric constant of polar LB films built up from molecules of p-(p-octadecyloxyphenylazo) benzenesulfonamide (18-OABS) with a large dipole moment. A significant pyroelectric effect in the films proved them to be polar. An irreversible transition at 90 °C from the polar to the nonpolar phase has been observed in these films. At this transition the structural period of the films changes (39 → 69 A). The films were found not to have a solid-to-liquid transition but a liquid-crystal state. In the liquid-crystal state the films have several smectic mesophases. Phase transitions take place at T1 = 112–116 °C, T 2 = 122–126 ° C (69 → 63 A ), T 3 = 134–138 ° C (63 → 41 A ) and T 4 = 150–155 ° C (41 A → melting ). A strong frequency dependence of the dielectric constant was observed at T > 120 °C.