Synthesis of Ras proteins and their application in biofunctional studies

We summarized the developed strategies including chemical total synthesis, biosynthesis and semi-synthesis for producing Ras proteins with modification and their application in biological studies.     

Solid-phase synthesis of palmitoylated and farnesylated lipopeptides employing the fluoride-labile PTMSEL linker

Acid- and base-labile S-palmitoylated and S-farnesylated lipopeptides can be synthesized in high overall yield employing the (2-phenyl-2-trimethylsilyl) ethyl (PTMSEL) linker for anchoring to and release under almost neutral conditions from the solid support.     

Rational design,properties, and applications of biosurfactants: a short review of recent advances

Biosurfactants combine physicochemical properties with biological activities. Although biosurfactants are often expressed by microorganisms, an increasing amount is produced by chemical synthesis. As many exist in the form of homologous compounds, it is often difficult to purify biosurfactants. But this has not limited the efforts to develop their commercial applications. In this short review, we have featured the recent advances in three important types of biosurfactants, lipopeptides, nucleolipids, and glycolipids. We have focused on comparing some of the key properties and functionalities between modern synthetic versions and their corresponding natural counterparts. We end the review by outlining the needs for not only strengthening their basic structure–property relationships through further research but also developing better technologies, irrespective of direct chemical synthesis or biological synthesis of biosurfactants through constructions of genetically engineered strains, to help advance the commercial use of biosurfactants.     

Optimization of Spore and Antifungal Lipopeptide Production During the Solid-state Fermentation of <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Bacillus subtilis strain TrigoCor 1448 was grown on wheat middlings in 0.5-l solid-state fermentation (SSF) bioreactors for the production of an antifungal biological control agent. Total antifungal activity was quantified using a 96-well microplate bioassay against the plant pathogen Fusarium oxysporum f. sp. melonis. The experimental design for process optimization consisted of a 2⁶⁻¹ fractional factorial design followed by a central composite face-centered design. Initial SSF parameters included in the optimization were aeration, fermentation length, pH buffering, peptone addition, nitrate addition, and incubator temperature. Central composite face-centered design parameters included incubator temperature, aeration rate, and initial moisture content (MC). Optimized fermentation conditions were determined with response surface models fitted for both spore concentration and activity of biological control product extracts. Models showed that activity measurements and spore production were most sensitive to substrate MC with highest levels of each response variable occurring at maximum moisture levels. Whereas maximum antifungal activity was seen in a limited area of the design space, spore production was fairly robust with near maximum levels occurring over a wider range of fermentation conditions. Optimization resulted in a 55% increase in inhibition and a 40% increase in spore production over nonoptimized conditions.     

A New Antifungal Cyclic Lipopeptide from Bacillus marinus B‐9987

A new cyclic lipopeptide, marihysin A ( 1 ), along with the three known cyclodipeptides cyclo(Ala‐Ile) ( 2 ), cyclo(Ala‐Leu) ( 3 ), and cyclo(Ala‐Tyr) ( 4 ), was isolated from the fermentation broth of the marine microorganism Bacillus marinus B‐9987 isolated from the tissues of rhizophere of Suaeda salsa in the intertidal zone of the Bohai Bay of P. R. China. Marihysin A ( 1 ) was established to be cyclo(Pro‐Gln‐Asn¹‐Ser‐Asn²‐Tyr‐Asn³‐β‐aminotetradecanoic acid) by spectroscopic analysis, and it exhibits broad‐spectrum but low activity against plant pathogens as determined by antifungal bioassay.     

Effect of variation in the chain length and number in modulating the interaction of an immunogenic lipopeptide with biomembrane models

A differential scanning calorimetry study was carried out to investigate the effect exerted by immunogenic synthetic lipopeptides obtained by the conjugation of LCMV_33–41 peptide with lipoamino acids (Laas) bearing different alkyl chain lengths (C₁₂ and C₁₆) and number of chains (2 × C₁₂) on the thermotropic behaviour of dimyristoylphosphatidylcholine (DMPC) liposomes. The aim of this work was to study the ability of these compounds to be carried by a liposomal system and released to a biomembrane model.

The examined compounds caused variations of the thermotropic parameters that characterise the liposomal system (transition temperature, T_m and enthalpy variation, ΔH), and interacted with the biomembrane models in different way. The interaction was found to be modulated by the length and number of chains present in the examined compounds. In fact, the compounds with higher number of lipid chain showed a stronger interaction with the biomembrane models with respect to the pure peptide and the compounds with a single lipid chain. These results suggest that the lipoamino acid moiety could favour the peptide to be carried by the liposomal system and released to biomembrane.