Protein and Peptide Letters - Volume 17, Issue 11, 2010

Antimicrobial peptides (AMPs) are a class of defence peptides that selectively target micro-organisms in order to protect the host. AMPs form part of the innate immune system of organisms such as plants (thormatin), insects (ceratoxin), amphibians (magainins, brevins, aureins) and mammals (indolicidin, LL-37, defensins, dermaseptin) [1-4]. Many of these peptides are cationic, composed of 10 to 45 amino acids, and adopt am Read More

Antimicrobial peptides (AMPs) are short, cationic, membrane-interacting proteins that exhibit broad-spectrum antimicrobial activity, and are hence of significant biomedical interest. They exert their activity by selectively binding to and lysing target cell membranes, but the precise molecular details of their mechanism are not known. This is further complicated by the fact that their structural characteristics are dependent upo Read More

We have synthesized a series of short peptides (17 to 20 amino acids), originally derived from Limulus antilipopolysaccharide factor LALF, which were primarily designed to act as antimicrobial agents as well as neutralizers of bacterial endotoxin (lipopolysaccharide, LPS), Here, two selected peptides, a 17- and a 19-mer, were characterized physicochemically and in biological test systems. The secondary structure of the pepti Read More

Amphipathic peptides are accommodated within the diffuse gradient of polarity that characterizes the interfacial regions of phospholipid bilayer membranes. Interfacial membrane interactions are key to the diverse biological functions and activities of these peptides, which encompass a large class of antimicrobial peptides including the helical peptides magainin, melittin, and RTA3 derived from the commensal bacterium Strept Read More

Differential Scanning Calorimetry studies of a synthetic peptide revealed the peptide decreased the temperature of the lamellar-hexagonal phase transition of cis-trans mixtures of phosphatidylethanolamine. The transition enthalpy varied significantly with lipid composition. The findings are discussed with reference to peptide saturation on the bilayer surface, bilayer thinning and peptide orientation.

Here we present data on the kinetics of insertion of melittin, a peptide from bee venom, into lipid membranes of different composition. Another component of bee venom is the enzyme phospholipase A2 (PLA2). We have examined the interaction of melittin and PLA2 with liposomes both separately and combined and demonstrate that they work synergistically to disrupt the membranes. A dramatic difference in the action Read More

The Langmuir Blodgett apparatus provides a versatile system for studying the interfacial properties of peptides and peptide-membrane interactions under controlled conditions. Using amphiphilic α-helical peptides to highlight studies undertaken, here we discuss the use of this system to provide information on the surface activity of peptides and describe the insights these studies give into biological function.

Tyrosine hydroxylase is studied in terms of adsorption behaviour on gold surfaces and various passivating layers. Results reveal differences in layer formation, where mercaptoundecanoic acid-coated gold shows the best potential in terms of adsorbed mass. Nanoparticles with this coating are subsequently tested for enzymatic activity, which remains at attenuated levels.

QseC is a histidine kinase (HK) receptor involved in quorum sensing, a mechanism by which bacteria respond to fluctuations in cell population. We conducted a structural study of the cytoplasmic domain of QseC (QseC-CD) using X-ray crystallography. The 2.5 Å structure of the apo-enzyme revealed that the kinase domain of QseC retains the overall fold of the typical HK kinase domain. The construct that we used is inactive i Read More

The paper deals with investigation of silver ion interaction with sulfur-bearing amino acids and cysteinebearing peptides using an electrospray ionisation orthogonal ion introduction time-of-flight (ESI-o-TOF) mass spectrometer. It has been shown that Cys and Hcy demonstrate the largest affinity for silver, both in relation to methionine and cysteine residues in peptides. The studies have for the first time revealed the effect Read More

We evaluated the i-peptides occurrence frequency in the protein sequences, belonging to two reference datasets containing structured and disordered protein domains. Moreover we estimated the most frequent i-peptides (with i= 2, 3, 4) into these sequences in order to select specific i-peptides for each structural classification. According to these specific ipeptides, a new binary classification method was developed for pr Read More

Cyclodextrin glycosyltransferase (EC 2.4.1.19, CGTase) is an important industrial enzyme in the production of cyclodextrins. Thermal stability is of great importance for this enzyme. Rational design of thermostable variants of mesophilic proteins is well motivated. In this work, molecular dynamics simulations have been performed to study thermal stabilization of CGTase protein via electrostatic interactions of salt bridges. Read More

In this work, we have compared the stability and activity of immobilized lipase and free enzyme of same specific activity. The immobilization was carried out on (3Å x 1.5 mm) molecular sieve (a porous support) derivatized with glutaraldehyde as the functional group. Immobilization of the enzyme allowed the maintenance of 85% of the enzyme activity even after 8th cycle. In fact, only 12% of the enzyme activity was lost w Read More

Microarray technologies have begun to feature widely in biomedical science. These techniques, allow for high throughput and quantitative analysis of protein-carbohydrate interactions. Lectin and antibody have been evaluated with these new techniques which extend to the detection of viruses and bacteria. This review outlines some of the basic principles of ‘glycoarrays’ and illustrates their recent applications. Moreover, the re Read More

The effects of mixed crowding agents containing both sucrose and dextran 70 on refolding process of human muscle creatine kinase (HCK) were studied by enzyme activity assay and aggregation measurements. The results showed that sucrose and dextran have opposite effect on parameters of HCK during refolding: reactivation yield, refolding rates and amount of aggregation, as they were both used in the mixed Read More

The polypeptide leptin exerts a multitude of regulatory functions. It has been implicated in the pathophysiology of inflammatory, metabolic and psychiatric disorders and has been found to be differentially expressed in men and women. Although a clear increase of leptin levels with age has been repeatedly observed in men, the association of leptin levels and age in women is an issue of scientific discussion. To investigate the Read More

Predicting enzyme subfamily class is an imbalance multi-class classification problem due to the fact that the number of proteins in each subfamily makes a great difference. In this paper, we focus on developing the computational methods specially designed for the imbalance multi-class classification problem to predict enzyme subfamily class. We compare two support vector machine (SVM)-based methods for the imbala Read More

Proteins perform various functions through interacting with other molecules. Analyzing the characteristics of residues on the interaction interfaces provides insights into the mechanisms of these interactions. In this study, we analyze the characteristics of five different interfaces: protein-protein interfaces, protein-DNA interfaces, protein-RNA interfaces, protein-carbohydrate interfaces, and protein-ligand interfaces. The analysis r Read More