Aggregation State of the Glycoprotein Excreted by Pseudoalteromonas antarctica NF3 on a Support of Phosphatidylcholine Liposomes

Abstract

The aggregation state of the microfilm produced by the glycoprotein (GP) excreted by a new Gram-negative species, Pseudoalteromonas antarctica NF 3 , on a support of phosphatidylcholine (PC) liposomes was examined by transmission electron microscopy (TEM). Image analysis profiles of digitized freeze-fracture TEM micrographs show that the outer covering film (PC:GP weight ratio 8:2) consisted in a multilayer structure formed by 9-10 layers. The periods of the average distance of the pattern ordering in layers were of about 2.3 nm, and the thickness of the complete film was of about 25 nm. The fact that the protective effect against sodium dodecyl sulfate of PC liposomes prepared in the presence ofGP sharply increased with respect to that obtained when liposomes were only outwardly coated by this compound indicates that in the first case the GP multilayer structure also affected the inner monolayer of liposomes. Image analysis of freeze-fracture TEM showed that the coatings present in these two types of liposomes had the same structure despite that the number of external layers in the first case was almost the half than that in the second.