Effect of protein charge on the generation of aggregation-prone conformers.

This study describes how charge modification affects aggregation of ovalbumin, thereby distinguishing the role of conformational and electrostatic stability in the process. Ovalbumin variants were engineered using chemical methylation or succinylation to obtain a range of protein net charge from -1 to -26. Charge modification significantly affected the denaturation temperature.

Salivary protein/peptide profiling with SELDI-TOF-MS.

In this study, large-scale profiling of salivary proteins and peptides ranging from 2 to 100 kDa was demonstrated using surface-enhanced laser desorption/ionization-time of flight-mass spectrometry (SELDI-TOF-MS). Results show that chip surface type and sample type critically affect the amount and composition of detected salivary proteins. Delayed processing time resulted in both increase and decrease of peak numbers consistent with proteolysis.

Aggregation of beta-lactoglobulin regulated by glucosylation.

A large number of proteins are glycosylated, either in vivo or as a result of industrial processing. Even though the effect of glycosylation on the aggregation of proteins has been studied extensively in the past, some reports show that the aggregation process is accelerated, whereas others found that the process is inhibited by glycosylation. This paper investigates the reasons behind these controversial results as well as the potential mechanism of the effect of glucosylation on aggregation using bovine beta-lactoglobulin as a model.

Deglycosylation of ovalbumin prohibits formation of a heat-stable conformer.

To study the influence of the carbohydrate-moiety of ovalbumin on the formation of the heat-stable conformer S-ovalbumin, ovalbumin is deglycosylated with PNGase-F under native conditions. Although the enzymatic deglycosylation procedure resulted in a complete loss of the ability to bind to Concavalin A column-material, only in about 50% the proteins lost their complete carbohydrate moiety, as demonstrated by mass spectrometry and size exclusion chromatography. Thermal stability and conformational changes were determined using circular dichroism and differential scanning calorimetry and demonstrated at ambient temperature no conformational changes due to the deglycosylation.

SELDI-TOF-MS of saliva: methodology and pre-treatment effects.

Interest in saliva as a diagnostic fluid for monitoring general health and for early diagnosis of disease has increased in the last few years. In particular, efforts have focused on the generation of protein maps of saliva using advanced proteomics technology. Surface-enhanced laser-desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is a novel high throughput and extremely sensitive proteomic approach that allows protein expression profiling of large sets of complex biological specimens.

Genetic variation in pea seed globulin composition.

A quantitative characterization of seeds from 59 pea (Pisum sativum L.) lines and relative taxa with various external characteristics and wide geographical origin was performed to explore the genetic variation of pea concerning its starch and protein contents and globulin composition. Pea lines, which produce round, wrinkled, flat, and round-dimpled seeds, have starch as the major reserve, with an average content of 46%.

The presence of heat-stable conformers of ovalbumin affects properties of thermally formed aggregates.

The aim of this work was to study the effect of the formation of more heat-stable conformers of chicken egg ovalbumin during incubation at basic pH (9.9) and elevated temperature (55 degrees C) on the protein aggregation properties at neutral pH. Native ovalbumin (N-OVA) is converted on the hours time-scale into more heat-stable forms denoted I- (intermediate) and S-OVA, that have denaturation temperatures 4.

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

Processing of ovalbumin may result in proteins that differ more than 23 degrees 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 (glycosylation); 4) increasing the hydrophobic exposure (lipophilization); or by 5) processing under alkaline conditions and elevated temperature (S-ovalbumin). The effect on the structural fold was investigated using a variety of biochemical and spectroscopic tools.