Rôle d'un intermédiaire lipidique dans le transfert du mannose à des accepteurs glycoprotéiques endogènes chez Aspergillus niger

AbstractPrevious studies from this laboratory have shown that a particulate preparation from Aspergillus niger catalyses the incorporation of mannose, from GDP-mannose, into a lipid fraction which has been identified as polyprenyl phosphate mannose (PPM). The results of kinetic studies presented in this communication suggest that PPM serves as an intermediate in the ensymatic transfer of mannosyl unit from GDP-mannose to endogenous glycoproteins. β-elimination or Pronase treatment and subsequent dialysis result respectively in 70% or 90% release of radioactivity. The absence of passive penetration of GDP-mannose across microsome membranes and the inhibitory effect of palmityl-CoA on mannose transfer are in good agreement with the involvement of PPM in the transport of mannose across membranes

Systeme acellulaire d'incorporation du 1-14C-D mannose dans les glycoproteines d'aspergillus oryzae

AbstractThe smooth microsomal fractions from Aspergillus oryzae were shown to carry out transfer of mannose from GDP-mannose to endogenous proteins acceptors. Data also are presented which support that among the subcellular fractions, only the microsomes are active in the mannose transfer reaction. All of the radioactive material chromatographs with mannose, following acid hydrolysis of microsomal fractions

Purification and characterization of a glucoamylase secreted by <i>Sclerotinia sclerotiorum</i>

International audienc

Phason softening in the AlPdMn icosahedral phase

The diffuse scattering located close to Bragg reflections has been studied as a function of the temperature on a single grain of the AlPdMn icosahedral phase. Between $600^\circ$C and $800^\circ$C there is a reversible and continuous transition. When the temperature increases, the diffuse scattering diminishes whereas high-$Q_\bot$ reflections have their intensity increased. All results are well interpreted within the elasticity theory of quasi-crystals: the changes in diffuse scattering shape and intensity when lowering the temperature are due to a softening of the K1 phason elastic constant. The time decay of these long-wavelength phason fluctuations is larger than 5 ns