Biochimica et biophysica acta最新文献

Measurements in systems of enzymically inactive influenza viruses and sialoglycoproteins disclosed an equilibrium between the free reactants and the virus-glycoprotein complex. Equilibrium constants were determined by two methods: equilibrium filtration and ultracentrifugal separation. The glycoproteins tested were influenza virus haemagglutinin inhibitors of high potency (ovine submaxially glycoprotein) and low potency (fetuin, orosomucoid and trypsin-treated OSM). The equilibrium constants (in molar terms) were found to be 1·10⁻⁸ for OSM, 9·10⁻⁷ for fetuin, 2·10⁻⁵ for orosomucoid and 4·10⁻⁶ for the glycopeptides (assumed mol. wt. 50000) obtained by controlled trypsin treatment of OSM. Weight for weight OSM was 17 times more firmly bound to enzymically inactive Lee virus than were its constituent glycopeptides as formed on trypsin treatment.

The number of negatively charged terminal sialic acid residues attached simultaneously to complementary groupings at the virus surface, appears to determine primarily the inhibitory potency of the glycoproteins. This determinant is a compound of the number of sialic acid residues available per glycoprotein molecule and of the complementariness of the contacting areas on the surface of virus and glycoprotein.

Advantage has been taken of the macromoleculer-sieve effect of hyaluronic acid to increase resolution in the ultracentrifuge. Substances, which normally sediment at the same rate in salt solutions because of a similarity in their sedimentation coefficients can be separated in hyaluronic acid media if they differ in size and shape. By selecting suitable concentrations of hyaluronic acid it has proved possible to separate fibrinogen from γ-globulin; albumin from dextran; and a colloidal silica from a polystyrene latex. Like procedures revealed and unsuspected inhomogeneity in a dextran preparation and served to resolve the polyglucose into two fractions.

Mycoside C₂ from Mycobacterium avium is a mixture of two homologous peptidoglycolipids: C_2a (Formula III) and C_2b (Formula IV). Both have the following partial structure:

The C-terminal molecule of D-alanine esterifies the pseudoaldehydic function of 6-deoxy-L-talose in mycoside C_2a and that of $\text{3-O-}\text{methyl-6-deoxy-}\text{L}\text{-talose}$ in mycoside C_2b. One acetyl group is linked to 3,4-di-O-methylrhamnose and two acetyl groups to 6-deoxy-L-talose and to $\text{3-O-}\text{methyl-6-deoxy-}\text{L}\text{-talose}$.

the lipid moiety is an acid (or mixture of acids) RCOOH of approximate formula C₄₃H₈₆O₂ ± 3 CH₂, or C₄₆H₉₀O₃ ± 3 CH₂ bound by an amide linkage to the amino group of D-phenylalanine.

By fractional ultracentrifugation in ether it was possible to isolate peptidoglycolipid fractions from wax D of atypical, avian and saprophytic strains. The “heavy” fractions from wax D of the atypical strain No. 4 (Mycobacterium kansasii), of Mycobacterium avium and of Mycobacterium phlei contain a peptide moiety with alanine, glutamic acid and meso-α,α′-diaminopimelic acid in approximate molar ratio 3:2:2, similar to that isolated from wax D fractions of human strains. By mass spectrometry it was shown that the mycolic acids of wax D from the atypical photochromogenic strain N. 4 (M. kansasii) are of the “saprophytic” type.

d-Methionine is incorporated into the cell walls of Alcaligenes fecalis thereby blocking further synthesis of this stucture. In the present paper evidence is presented demonstrating incorporation of d-methionine into a component of the phenol-insoluble cell wall which may be liberated by lysozyme (N-acetylmuramide glycanohydrolase, EC 3.2.1.17). Chromatography of the products of lysozyme digestion indicate that d-methionine is incorporated into a complex structure, which can be broken into different units by lysozyme. Analysis has shown that neither the amino nor the carboxyl groups of methionine are free when this amino acid is incorporated into the cell wall. Electron-microscopic studies have revealed lesions in the wall of cells grown in the presence of d-methionine as well as the liberation of firbous material from the cell wall. This fibrous material appears to be lysozyme sensitive and may possibly originate from a more compact subunit.