A comparison of the surface activity of the fungal hydrophobin SC3p with those of other proteins

The fungal hydrophobin SC3p, a protein secreted by Schizophyllum commune, has become known to form SDS-insoluble layers and to change the physico-chemical properties of an interface. In this study, the surface activity of SC3p was studied by determining the interfacial tensions gamma iv and gamma sl during adsorption of SC3p at both the liquid-vapour and the solid-liquid interface utilizing the in situ technique axisymmetric drop-shape analysis by profile. To this end, protein solution droplets were put on the solid fluoroethylene-propylene-Teflon. At the liquid-vapour interface, SC3p caused a large decrease of gamma iv from 72 to 43 mJ m-2 at the concentration of 0.1 mg ml-1. At the solid-liquid interface, gamma sl was slightly decreased, whereas the contact angle theta increased, indicating an increase in hydrophobicity of FEP-Teflon, which is unique among the proteins studied so far. Earlier findings indicated a decrease in hydrophobicity of Teflon upon adsorption of SC3p, but this was after a washing and drying step. In order to reconcile these findings with those of the present study, adsorption of SC3p to hydrophobic surfaces is suggested to occur in bilayers. The second layer is supposed to be less strongly adsorbed than the first layer and can be easily removed by washing.     

Three Dimensional Domain Structure in Epitaxial Barium Titanate Thin Films

The three dimensional domain structure of barium titanate thin films was determined using a serial sectioning technique. The domain structure varied sharply through the film thickness, being primarily a-oriented near the substrate and increasingly c-oriented away from this interface. The variation in domain structure is explained in terms of a strain gradient due to partial relaxation of epitaxial coherency strains. The refractive index also varied through the film thickness. A simple relationship based on areal fraction of each domain type aptly described the changes in refractive index with domain structure. These results indicate the importance of understanding three-dimensional domain structure and its impact on film properties.     

Thin Film Ferroelectrics for Guided Wave Devices

Thin film ferroelectrics are being developed for guided wave optical devices. Of particular interest is BaTiO₃ because of its high electro-optic coefficient. Epitaxial thin films have been deposited by metalorganic chemical vapor deposition that are suitable for electro-optic devices. Thin film electro-optic modulators have been fabricated and their optical properties characterized. Factors that determine the ultimate bandwidth of these devices are discussed.     

Psychrotrophic, proteolytic and lipolytic properties of Enterobacteriaceae isolated from milk and dairy products

Most of the Enterobacteriaceae strains (73 out of 75) isolated in a previous study (Wessels et al., 1988) were psychrotrophic on agar plates, with the exception of Enterobacter cloacae strains. The Enterobacteriaceae strains were largely non-proteolytic on milk agar medium although limited numbers of E. cloacae, Serratia rubidaea and Klebsiella oxytoca strains were capable of proteolytic activity at 25 degrees C. The E. cloacae and K. oxytoca strains positive at 25 degrees C were also proteolytic at 7 degrees C. Most of the species tested were non-lipolytic on Victoria blue butterfat agar. The majority of Serratia marcescens and Klebsiella pneumoniae strains and a minority of E. cloacae and K. oxytoca strains, however, were lipolytic on this medium.     

Nachweis der Glyceride veresterter Olivenöl-Fettsäuren

Detection of the Glycerides of Esterified Olive Oil Fatty Acids Natural olive oil and ester oil with the same fatty acid composition contain approximately the same amount of dipalmito-olein (ca. 4%) and palmito-diolein (ca. 20%). The positional isomers of these glycerides which contain palmitic acid in the 2-position, occur in very small amount in olive oil but are present in considerably larger amount in ester oil. The same is also true for the corresponding stearic acid containing glycerides. The dipalmito-olein and palmito-diolein containing fractions were isolated by silver nitrate chromatography. The characteristic ratios of the positional isomers (POP/PPO and POO/OPO) in both the oils are determined indirectly by enzymatic hydrolysis of the fatty acids in 1,3-position and analysing the 2-monoglyceride fatty acids gas chromatographically.     

Die DC-Trennung von isomeren und natürlichen Triglycerid-Gemischen

TLC-Separation of Mixtures of Isomeric and Natural Triglycerides Triglycerides can be separated by reverse phase as well as by argentation chromatography. In both of these methods critical pairs are formed whose separation can be effected to a large extent by a combination of the two methods. However, isomeric triglycerides can not be separated by the latter procedure. According to their structure, the isomeric triglycerides can be classified into positional isomers, geometric isomers, isomers having the same number of double bonds and C-atoms but containing different fatty acids, and glycerides containing the positional isomers of unsaturated fatty acids. The difficulties involved in the separation of these isomers are pointed out and examples for the TLC-separation of triglycerides of each class are shown. In addition to the resolution of model substances, the TLC-separations of cottonseed, sunflower, olive, peanut and palm kernel oils are given.     

The fatty acid composition of the lipids from two species of hake

The fatty acid composition of lipids extracted from the livers, muscle and skin of two hake species Merluccius capensis and M. paradoxus were studied. In one instance a comparison was made between the fatty acid composition of the phospholipid and triglyceride fractions of the lipids. In pre-spawning fish there appears to be a tendency for M. capensis to have fat of higher unsaturation than M. paradoxus. The only consistent species difference found was the high level of unsaturation of skin lipids relative to muscle lipids in M. paradoxus, a species living at greater depth and lower water temperatures. The major saturated fatty acid in hake lipids is that with 16 carbon atoms, the major monoenoic acid the one with 18 carbon atoms, while C_22:6 is the dominant polyenoic fatty acid and C_20:5 the second most plentiful in hake lipids. Phospholipids form a small proportion of the lipid from dark muscle. They are particularly rich in the fatty acids C_16:0 and C_22:6.