Purification and properties of membrane-bound methane hydroxylase from <Emphasis Type="Italic">Methylococcus capsulatus</Emphasis> (Strain M)

Membrane fraction of Methylococcus capsulatus (strain M) were treated with [¹⁴C]acetylene, an affinity label binding to the active center of membrane-bound methane monooxygenase (MMO). High-purity particulate form of methane hydroxylase (pMH) was obtained by ion exchange and hydrophobic chromatography. According to SDS-PAGE data, the enzyme contained three polypeptides with molecular weights of 47 (α), 27 (β), and 25 (γ) kDa in the ratio 1: 1: 1. The radiolabel was contained in the β-subunit of pMH. The protein contained 1 or 2 atoms of nonheme iron and 2–4 atoms of copper per a minimum molecular weight of 99 kDa. This protein did not oxidize methane or propylene in the presence of NADH but was able to oxidize low quantities of methane in the presence of duroquinol. It was established that methanol dehydrogenase (MD) and NADH oxidoreductase (NADH-OR) are peripheral membrane proteins. Possible causes of low activity of high-purity methane hydroxylase are discussed.     

Construction of peptide mimetics of an epitope of the human immunodeficiency virus (HIV-1) gp41 protein, recognized by virus-neutralizing antibodies 2F5

A phase peptide library was screened with virus-neutralizing monoclonal antibodies (MCA) 2F5 which recognize a conserved epitope of HIV-1 gp41. Phages that expose peptides specifically binding with MCA 2F5 were selected by ELISA. Amino acid sequence analysis revealed a homology to region 662-671 of HIV-1 HB10 gp160 for most peptides. The major role in recognition was ascribed to Asp-664, Lys-665, and Trp-666. The epitope-mimicking peptides were tested for immunogenicity. Antibodies to gp41 were detected in serum of immunized rabbits.     

Determination of glycyrrhizic acid binding sites by a phage display method

Phages that expose peptides specifically interacting with glycyrrhizic acid (GA) were selected from a phage peptide library by affinity selection and ELISA. Amino acid sequence analysis of the selected peptides and human proteins with the SIM program revealed homology to tyrosine protein kinases, serine/threonine protein kinases, tyrosine phosphatases, and some receptors. Analysis of the peptide and virus protein sequences with the BLAST program showed that GA has affinity for various surface proteins of several human viruses such as HIV-1, hepatitis C virus, and herpesviruses.     

Immunogenic Properties of Peptides Mimicking a HIV-1 gp41 Epitope Recognized by Virus-Neutralizing Antibodies 2F5

Phage display was used to obtain peptides mimicking a HIV-1 gp41 conserved epitope recognized by virus-neutralizing monoclonal antibodies (mAb) 2F5. Rabbits and mice were immunized with the peptides exposed on the surface of filamentous bacteriophages. Antibodies to gp41 were detected in the sera of immunized animals. The virus-neutralizing activity of the sera was examined.     

Localization of the HIV-1 gp120 Conformational Epitope Recognized by Virus-Neutralizing Monoclonal Antibodies 2G12

A phage peptide library was used to select peptides interacting with virus-neutralizing monoclonal antibodies (mAb) 2G12 which recognize a discontinuous surface epitope of HIV-1 gp120. With the published X-ray data, gp120 regions involved in the antigenic determinant were predicted. Binding with mAb 2G12 was ascribed to Thr297, Phe383, Tyr384, Arg419, Ile240, Thr415, Leu416, Pro417, Lys421, and Trp112. Though distant in the gp120 sequence, these residues are close in space and form the 2G12 epitope on the gp120 surface.     

Comparative study of the structural organization of the 2 divisions of the hindbrain of 10-day-old chick embryos

Light and electron microscopic investigation has been made of the main structural components of the nervous tissue in two divisions of the telencephalon (the dorsal ventricular ridge and striatum) in 10-day chick embryos. Special attention was paid to the degree of maturation of cellular elements of the nervous tissue, the development of neuropil and the level of synaptogenesis. The data obtained suggest heterochronous maturation of the divisions investigated. Striatum, being phylogenetically more ancient structure, is formed prior to the dorsal ventricular ridge.     

Glycoproteins and glycolipids in intercellular interactions]

Glycoproteins and glycolipids as important constituents of the extracellular matrix are considered in the present review. Their role in the processes of cell-to-cell contacts, control of cell proliferation and neoplactic transformation, are discussed. A glycosyltransferase-acceptor model of cellular recognition is also given.     

Control of cell multiplication in vitro. V. The dependence of cell multiplication on the ganglioside content

The concentration and composition of gangliosides in the cells of L-line and its clones--L-2 and Lebr 1/1, with values of saturation densities being 0.9, 1.6 and 3.2 X 10(5) cells/mc2, respectively, were compared. The transition of populations in the stationary growth phase was shown to be accompanied by an increment of ganglioside concentration and accumulation of di- and three-sialogangliosides. The data obtained are discussed in connection with the previously published results about changing intracellular cAMP content and conA-mediated agglutination at density-dependent growth inhibition L-cell variants.