Reversible self-association of ovalbumin at air-water interfaces and the consequences for the exerted surface pressure

In this study the relation between the ability of protein self-association and the surface properties at air-water interfaces is investigated using a combination of spectroscopic techniques. Three forms of chicken egg ovalbumin were obtained with different self-associating behavior: native ovalbumin, heat-treated ovalbumin-being a cluster of 12...

Quantitative description of the relation between protein net charge and protein adsorption to air-water interfaces

In this study a set of chemically engineered variants of ovalbumin was produced to study the effects of electrostatic charge on the adsorption kinetics and resulting surface pressure at the air-water interface. The modification itself was based on the coupling of succinic anhydride to lysine residues on the protein surface. After purification of...

Glycoforms of β-Lactoglobulin with Improved Thermostability and Preserved Structural Packing

In this article we show how various degrees of glycosylation can be used to control the thermal stability of proteins. The primary amines of β-lactoglobulin were glycosylated with glucose or fructose within a range of non-denaturing reaction parameters. The modified fractions were characterized and analyzed for structural stability and...

Characterization of Pea Vicilin. 1. Denoting Convicilin as the α-Subunit of the Pisum Vicilin Family

Vicilin, a major globulin protein of pea that has been described as "extremely heterogeneous in terms of its polypeptide composition", was extracted from pea flour under alkaline conditions and subsequently fractionated by salt under acid conditions. This procedure induced the separation of vicilin into two fractions, which, after purification,...

Transglutaminase-Mediated Modification of Glutamine and Lysine Residues in Native Bovine β-Lactoglobulin

Bovine β-lactoglobulin (BLG) is a major component in whey and its physical properties are important for the texture of many dairy-based foods. Modification of proteins with transglutaminase from Streptoverticillium mobaraense (MTGase) can be used to alter their physical properties. MTGase-mediated modification of native BLG was until now,...

Modification of β-lactoglobulin by oligofructose: Impact on protein adsorption at the air-water interface

Maillard products of β-lactoglobulin (βLg) and fructose oligosaccharide (FOS) were obtained in different degrees of modification depending on incubation time and pH. By use of a variety of biochemical and spectroscopic tools, it was demonstrated that the modification at limited degrees does not significantly affect the secondary, tertiary, and...

Tentative assignment of the potato serine protease inhibitor group as β-II proteins based on their spectroscopic characteristics

Potato serine protease inhibitor (PSPI) is the most abundant protease inhibitor group in potato tuber. The investigated PSPI isoforms have a highly similar structure at both the secondary and the tertiary level. From the results described, PSPI is classified as a β-II protein based on (1) the presence in the near-UV spectra of sharp peaks,...

Chemical processing as a tool to generate ovalbumin variants with changed stability

Processing of ovalbumin may result in proteins that differ more than 23°C in denaturation temperature while the structural fold is not significantly affected. This is achieved by 1) conversion of positive residues into negative ones (succinylation); 2) elimination of negative charges (methylation); 3) reducing the proteins hydrophobic exposure ...

Structure and dynamics of egg white ovalbumin adsorbed at the air/water interface

The molecular properties of egg white ovalbumin adsorbed at the air/water interface were studied using infrared reflection absorption spectroscopy (IRRAS) and time-resolved fluorescence anisotropy (TRFA) techniques. Ovalbumin adsorbed at the air/ water interface adopts a characteristic partially unfolded conformation in which the content of the...

Structural and functional analysis of the S-layer protein crystallisation domain of Lactobacillus acidophilus ATCC 4356 : evidence for protein : protein interaction of two subdomains

The structure of the crystallisation domain, SAN, of the S A-protein of Lactobacillus acidophilus ATCC 4356 was analysed by insertion and deletion mutagenesis, and by proteolytic treatment. Mutant S A-protein synthesised in Escherichia coli with 7-13 amino acid insertions near the N terminus or within regions of sequence variation in SAN (amino...

The S-layer protein of Lactobacillus acidophilus ATCC 4356: Identification and characterisation of domains responsible for S-protein assembly and cell wall binding

Lactobacillus acidophilus, like many other bacteria, harbors a surface layer consisting of a protein (SA-protein) of 43 kDa. SA-protein could be readily extracted and crystallized in vitro into large crystalline patches on lipid monolayers with a net negative charge but not on lipids with a net neutral charge. Reconstruction of the S-layer from...

Dephosphorylation-induced structural changes in β-casein and its amphiphilic fragment in relation to emulsion properties

To promote the understanding of the relationship between emulsifying and molecular properties of proteins/peptides, intact β-casein (βCN) and its amphipathic fragment, i.e. βCN (1-105/107) were dephosphorylated. Dephosphorylation was found not to change significantly their emulsifying properties. Since it is known that the structure of proteins...

Soy glycinin Influence of pH and ionic strength on solubility and molecular structure at ambient temperatures

This study describes the relationship between the solubility of glycinin, a major soy protein, and its structural properties at a quaternary, tertiary, and secondary folding level under conditions representative for food products. When the ionic strength is lowered from 0.5 to 0.2 or 0.03, the basic polypeptides shift more to the exterior of the...

Localization of synthesis of β1,6-glucan in Saccharomyces cerevisiae

β1,6-Glucan is a key component of the yeast cell wall, interconnecting cell wall proteins, β1,3-glucan, and chitin. It has been postulated that the synthesis of β1,6-glucan begins in the endoplasmic reticulum with the formation of protein-bound primer structures and that these primer structures are extended in the Golgi complex by two putative...

The adsorption-induced secondary structure of β-casein and of distinct parts of its sequence in relation to foam and emulsion properties

Changes in the secondary structure upon adsorption of β-casein (βCN) and of distinct parts of its sequence were investigated by far-ultraviolet circular dichroism in order to find suggested relationships with foam and emulsion-forming and -stabilising properties of the same protein/peptides. A teflon/water interface was used as a model system...

Heat-induced conformational changes of patatin, the major potato tuber protein

This paper presents a first structural characterization of isolated patatin, the major potato tuber protein, at ambient and elevated temperatures. Isolated patatin at room temperature is a highly structured molecule at both secondary and tertiary levels. It is estimated from far-ultraviolet circular dichroism data that about 33% of the residues...

Secondary structure of the intact H+,K+ -ATPase and of its membrane-embedded region. An attenuated total reflection infrared spectroscopy, circular dichroism and Raman spectroscopy study

Models of P-type ATPase predict that membrane-embedded fragments represent about 20% of the protein and adopt an all-α-helical structure. While this prediction was confirmed for the Ca2+ -ATPase [Corbalan-Garcia, S., Teruel, J., Villalain, J. and Gomez-Fernandez, J. (1994) Biochemistry 33, 8247-8254], it is at odds with recent experimental...

Molecular characterization of a saline-soluble lectin from a parasitic fungus: Extensive sequence similarities between fungal lectins

It has been proposed that the interactions between several parasite and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene...