Purification and properties of enolase from carp (Cyprinus carpio). Comparison with enolases from mammals' muscles and yeast

Dramatic Changes in Oligomerization Property Caused by Single Residue Deletion in Staphylococcus aureus Enolase

Studies were conducted to understand the role of C-terminal lysine residues in the catalytic activity, structural stability and oligomeric properties of Staphylococcus aureus enolase. Interestingly, the S. aureus enolase, in solution, shows its presence as a stable dimer as well as the catalytically active fragile octamer. Compared to the hexa-histidine tagged S. aureus enolase (rSaeno), the deletion mutant showed the negligible difference in K_m, but approximately 20-25% reduction in maximum reaction velocity (V_max) and 2% reduction in turnover number were observed. These kinetic parameters indicate that K-434Δ deletion mutation does not drastically compromise the enzyme efficiency. The secondary structure and the octameric conformation of both the rSaeno and the K-434Δ mutant are very much stable between pH ranging from 6 to 9, temperatures ranging from 20 to 40 °C and in the presence of divalent metal ions Mg²⁺, Zn²⁺ and Mn²⁺. Under these conditions, the recombinant enzyme and the mutant are also catalytically very active. Intrinsic tryptophan fluorescence (320-380 nm) and CD spectral (195-260 nm) analysis revealed that the secondary structure and the surface architecture of the proteins are not majorly altered by the mutation. But, a significant correlation was observed between the time-dependent decrease in the catalytic activity and the oligomeric stability of rSaeno and K-434Δ mutant. The C-terminal lysine residues in the inter-dimer groove aid in folding and oligomerization of S. aureus enolase.

A review on food processing and preparation methods for altering fish allergenicity

People eat many varieties of food to satiate their hunger. Among them, a few numbers of food cause overreaction of the body's immune system, and fish holds a permanent position on that list. Processing methods, including one treatment or a combination, can have different effects on the allergenic potential of food proteins. An important point to note, however, is that not all of these methods can eliminate the potential for protein allergy. Thus, it is essential to understand the risk involved with the consumption of processed fish and its derivatives. Fish could be prepared in various ways before come to the dining plate. It has shown some of these methods can effectively manipulate the allergenicity owing to the alterations occurred in the protein conformation. This article provides an overview of the impact of fish processing methods (thermal and non-thermal) on the allergenic potential of fish along with possible causative structural modification provokes allergen stability. The article begins with current trends related to fish consumption, proceeds with the prevalence and underlying mechanism of fish allergy. Properties of clinically relevant fish proteins, projected IgE epitopes of PV, cross-reactivity of fish allergens are also addressed in this context to understand and compare the behavioral patterns of PV profiles of different species on processing methods.

Molecular cloning, expression and characterization of enolase from adult Haemonchus contortus

Enolase represents a multifunctional protein involved in basic energy metabolism. In the present research, the enolase gene of Haemonchus contortus (HcENO) was cloned and characterized. Specific primers for the rapid amplification of cDNA ends (RACE) were designed based on the expression sequence tag (EST, GenBank Accession No. BF422728) to amplify the 3'- and 5'-ends of HcENO. The full length of cDNA from this gene was obtained by overlapping the sequences of 3'- and 5'-extremities and amplification by reverse transcription PCR. The biochemical activities of the recombinant protein HcENO, which was expressed in prokaryotic cells and purified by affinity chromatography, were analyzed by assays of enzymatic activity, stability to pH. The results showed that the cloned full length cDNA comprised 1583 bp and encoded a peptide with 434 amino acid residues which showed sequence similarity to several known enolases. The biochemical assay showed that the protein encoded by the HcENO exhibited enzymatic activity, whilst the HcENO was stable between pH 6 and 8. The natural enolase of H. contortus detected by immunoblot assay was approximately 49 kDa in size, and the recombinant HcENO was recognized strongly by serum from experimentally infected goats.

Molecular cloning and functional expression of enolase from Trichinella spiralis

The cDNA library was constructed from muscle larvae of Trichinella spiralis, and immunoscreened with sera from mice infected with T. spiralis. A cDNA clone, designated as TsENO, encoded 2-phospho-D-glycerate hydro-lyase (enolase) that catalyzed a reversible conversion of 2-phospho-D-glyceric acid (2PGA) to phosphoenolpyruvate (PEP) in the glycolytic pathway. The recombinant TsENO protein was produced in an Escherichia coli expression system. The recombinant full-length TsENO protein had no activity in the conversion of 2PGA to PEP, but gained enolase activity after cutting off the signal peptide from the full-length protein. There was no meaningful difference in the expression level of TsENO gene at three distinct stages of T. spiralis. Also, antibody against the recombinant TsENO protein reacted with crude extract of muscle larvae, but not with the excretory and secretory products.