Rapid Identification of Malaria Vaccine Candidates Based on α-Helical Coiled Coil Protein Motif

To identify malaria antigens for vaccine development, we selected α-helical coiled coil domains of proteins predicted to be present in the parasite erythrocytic stage. The corresponding synthetic peptides are expected to mimic structurally “native” epitopes. Indeed the 95 chemically synthesized peptides were all specifically recognized by human immune sera, though at various prevalence. Peptide specific antibodies were obtained both by affinity-purification from malaria immune sera and by immunization of mice. These antibodies did not show significant cross reactions, i.e., they were specific for the original peptide, reacted with native parasite proteins in infected erythrocytes and several were active in inhibiting in vitro parasite growth. Circular dichroism studies indicated that the selected peptides assumed partial or high α-helical content. Thus, we demonstrate that the bioinformatics/chemical synthesis approach described here can lead to the rapid identification of molecules which target biologically active antibodies, thus identifying suitable vaccine candidates. This strategy can be, in principle, extended to vaccine discovery in a wide range of other pathogens

The dissociation constants of methyl alkyl ketone cyanohydrins

The dissociation constants of a series of methyl alkyl ketone cyanohydrins have been measured by NMR spectroscopy. The heats of solutions of the ketones and the cyanohydrins have been determined. The effect of alkyl groups on the heats of solution have been shown to be unimportant in determining the observed dissociation constants of the cyanohydrins of these ketones

Proton Magnetic Resonance Studies of the Decomposition of 4-Hydroxycyclophosphamide, a Microsomal Metabolite of Cyclophosphamide

The proposed tautomeric equilibrium between the microsomal metabolite of cyclophosphamide, 4-hydroxycyclophosphamide, and the open chain aldophosphamide, and the subsequent facile β-elimination to generate acrolein and phosphoramide mustard have been confirmed by proton magnetic resonance studies. When 4-hydroxycyclophosphamide, initially maintained in CDC1 3 at −20°C, was allowed to equilibrate at 15°C, a singlet at 9.76 δ and a triplet at 2.88 δ appeared concomitantly which were assigned to the aldehydic proton and the protons α to the carbonyl of aldophosphamide, respectively. Further reaction led to the appearance of several NMR signals that indicated the irreversible formation of acrolein (multiplet at 9.55 δ) and phosphoramide mustard. Polymerization occurred approximately 2 hours after the initiation of the reaction. The kinetic data of the reaction sequence are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41423/1/11095_2004_Article_307226.pd

The Tharsis mantle source of depleted shergottites revealed by 90 million impact craters

International audienceThe only martian rock samples on Earth are meteorites ejected from the surface of Mars by asteroid impacts. The locations and geological contexts of the launch sites are currently unknown. Determining the impact locations is essential to unravel the relations between the evolution of the martian interior and its surface. Here we adapt a Crater Detection Algorithm that compile a database of 90 million impact craters, allowing to determine the potential launch position of these meteorites through the observation of secondary crater fields. We show that Tooting and 09-000015 craters, both located in the Tharsis volcanic province, are the most likely source of the depleted shergottites ejected 1.1 million year ago. This implies that a major thermal anomaly deeply rooted in the mantle under Tharsis was active over most of the geological history of the planet, and has sampled a depleted mantle, that has retained until recently geochemical signatures of Mars' early history

Early crustal processes revealed by the ejection site of the oldest martian meteorite

International audienceAbstract The formation and differentiation of the crust of Mars in the first tens of millions of years after its accretion can only be deciphered from incredibly limited records. The martian breccia NWA 7034 and its paired stones is one of them. This meteorite contains the oldest martian igneous material ever dated: ~4.5 Ga old. However, its source and geological context have so far remained unknown. Here, we show that the meteorite was ejected 5–10 Ma ago from the north-east of the Terra Cimmeria—Sirenum province, in the southern hemisphere of Mars. More specifically, the breccia belongs to the ejecta deposits of the Khujirt crater formed 1.5 Ga ago, and it was ejected as a result of the formation of the Karratha crater 5–10 Ma ago. Our findings demonstrate that the Terra Cimmeria—Sirenum province is a relic of the differentiated primordial martian crust, formed shortly after the accretion of the planet, and that it constitutes a unique record of early crustal processes. This province is an ideal landing site for future missions aiming to unravel the first tens of millions of years of the history of Mars and, by extension, of all terrestrial planets, including the Earth