HNF/HTPB propellants: Influence of HNF particle size on ballistic properties

The burning rate characteristics of solid composite propellants can be modified via different methods. One of these is the application of different oxidizer particle sizes in the propellant. The effect of the use of fine and coarse particles of the oxidizer hydrazinium nitroformate (HNF) in hydroxyl-terminated polybutadiene (HTPB)-based...

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...

Purification, cloning and characterisation of two forms of thermostable and highly active cellobiohydrolase I (Cel7A) produced by the industrial strain of Chrysosporium lucknowense

Two forms of cellobiohydrolase I (CBH I, Cel7A) were purified from the culture ultrafiltrate of a mutant strain of the fungus Chrysosporium lucknowense, an industrial producer of cellulases and hemicellulases. The enzymes had different molecular masses (52 and 65 kDa, SDS-PAGE data) but the same pI (4.5). Peptide sequencing showed that a single...

A novel thermoreversible gelling product made by enzymatic modification of starch

Amylomaltases or D-enzyme (4-α-glucanotransferases; E.C. 2.4.1.25) are carbohydrate-active enzymes that catalyze the transfer of glucan units from one α-glucan to another in a disproportionation reaction. These enzymes are involved in starch metabolism in plants or maltose/glycogen metabolism in many microorganisms. The amylomaltase of the...

Amylomaltase of Pyrobaculum aerophilum IM2 produces thermoreversible starch gels

Amylomaltases are 4-alpha-glucanotransferases (EC 2.4.1.25) of glycoside hydrolase family 77 that transfer alpha-1,4-linked glucans to another acceptor, which can be the 4-OH group of an alpha-1,4-linked glucan or glucose. The amylomaltase-encoding gene (PAE1209) from the hyperthermophilic archaeon Pyrobaculum aerophilum IM2 was cloned and...

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...

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 ...

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°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- ...

Sample geometry as critical factor for stability research

Stability research on gun propellants has been widely performed by microcalorimetry since the 1980s. TNO Prins Maurits Laboratory has already a broad experience since the early 1970s. In the past many studies were performed, to investigate the influence of oxygen, humidity etc. Less attention was paid to two other important aspects, namely the...

Differences in denaturation of genetic variants of soy glycinin

In heat denaturation studies conducted in the past the genetic variants of glycinin have been considered as a homogeneous group of proteins. In this work the validity of this assumption was tested. It was found by calorimetric studies that glycinin denatures heterogeneously at pH 7.6. When the temperature of isothermal treatment is increased...

Heat-induced conformational changes of Ara h 1, a major peanut allergen, do not affect its allergenic properties

Ara h 1, a major peanut allergen was isolated, and its structure on secondary, tertiary, and quaternary level at ambient temperature was investigated using spectroscopic and biochemical techniques. Ara h 1 appeared to be a highly structured protein on a secondary level, possesses a clear tertiary fold, and is present as a trimeric complex. Heat...

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...