Current Protein and Peptide Science - Volume 7, Issue 6, 2006

Proteins play a fundamental role in membrane dependent processes and due to the inherently amphiphilic nature of the bilayer, such proteins must accommodate both polar and non-polar environments. In response, membrane interactive proteins adopt amphiphilic secondary structures, which can be subdivided into several general classes but it is generally accepted that amphiphilic α-helices form the major example of these cl Read More

Antimicrobial peptides (AMPs) are effector molecules of innate immune systems found in different groups of organisms, including microorganisms, plants, insects, amphibians and humans. These peptides exhibit several structural motifs but the most abundant AMPs assume an amphipathic α-helical structure. The α-helix forming antimicrobial peptides are excellent candidates for protein engineering leading to an optimization Read More

Endogenous peptide antibiotics (termed also host-defense or antimicrobial peptides) are known as evolutionarily old components of innate immunity. They were found initially in invertebrates, but later on also in vertebrates, including humans. This secondary, chemical immune system provides organisms with a repertoire of small peptides that act against invasion (for both offensive and defensive purposes) by occasion Read More

Cancer is a major cause of premature death and there is an urgent need for new anticancer agents with novel mechanisms of action. Here we review recent studies on a group of peptides that show much promise in this regard, exemplified by arthropod cecropins and amphibian magainins and aureins. These molecules are α-helical defence peptides, which show potent anticancer activity (α-ACPs) in addition to their establis Read More

The receptor mimetic and mast cell degranulating peptide mastoparan (MP) translocates cell membranes as an amphipathic α-helix, a feature that is undoubtedly a major determinant of bioactivity through the activation of heterotrimeric G proteins. Chimeric combinations of MP with G protein-coupled receptor (GPCR) ligands has produced peptides that exhibit biological activities distinct from their composite components. Thus, Read More

Antifreeze proteins (AFPs) and antifreeze glycoproteins (AFGPs), found in the body fluids of many species of polar fish allow them to survive in waters colder than the equilibrium freezing point of their blood and other internal fluids. Despite their structural diversity, all AF(G)Ps kinetically depress the temperature at which ice grows in a noncolligative manner and hence exhibit thermal hysteresis. AF(G)Ps also share the abi Read More

Nature has selected peptide motifs for protein functions. It is clear that specific sequence motifs can identify families of enzymes. These sequence motifs are one dimensional signatures and nature has also developed two dimension motifs which cannot be read in the one dimension of sequence language but can be detected in the three dimensional properties of a secondary structure. One of such motifs is tilted peptid Read More

Oblique orientated α-helices possess hydrophobicity gradients, which allow the parent α-helices to penetrate the membrane at a shallow angle, thereby destabilising membrane lipid organisation and promoting a range of biological processes. These α-helices occur in a variety of membrane interactive proteins and a number of techniques have been developed to guide their identification using sequence data alone. Hydropho Read More

The amphipathic helix (AH) motif is used by a subset of amphitropic proteins to accomplish reversible and controlled association with the interfacial zone of membranes. Functioning as more than mere membrane anchoring domains, amphipathic helices can serve as autoinhibitory domains to suppress the protein activity in its soluble form, and as sensors or modulators of membrane curvature. Thus amphipathic helices can bo Read More

Amphipathic surface-active helices enable peripheral proteins to perform a variety of important cellular functions such as: lipid association and transport, membrane perturbation and disruption in programmed cell death or antimicrobial activity, and signal transduction. Amphipathic helices that adopt a surface-active membrane location are also found in transmembrane proteins. Since they possess similar amino acid comp Read More

G-Protein Coupled Receptors (GPCRs) are one of the most important targets for pharmaceutical drug design. Over the past 30 years, mounting evidence has suggested the existence of homo and hetero dimers or higher-order complexes (oligomers) that are involved in signal transduction and some diseases. The number of reports describing GPCR oligomerization has increased, and in 2003, the organization of mouse rhod Read More