Abstract It is shown that Mo corrosion occurs very slowly in sulfur and sodium polysulfides at 623 K. The high Mo content of Hastelloy B (nominal composition Ni‐5 Fe‐28 Mo) results in a good corrosion protection when exposed to sulfur.
Abstract In living cells, microtubules (MTs) play pleiotropic roles, which require very different mechanical properties. Unlike the dynamic MTs found in the cytoplasm of metazoan cells, the specialized cortical MTs from Toxoplasma gondii , a prevalent human pathogen, are extraordinarily stable and resistant to detergent and cold treatments. Using single-particle cryo-EM, we determine their ex vivo structure and identify three proteins (TrxL1, TrxL2 and SPM1) as bona fide microtubule inner proteins (MIPs). These three MIPs form a mesh on the luminal surface and simultaneously stabilize the tubulin lattice in both longitudinal and lateral directions. Consistent with previous observations, deletion of the identified MIPs compromises MT stability and integrity under challenges by chemical treatments. We also visualize a small molecule like density at the Taxol-binding site of β-tubulin. Our results provide the structural basis to understand the stability of cortical MTs and suggest an evolutionarily conserved mechanism of MT stabilization from the inside.
Abstract A method is described for synthesizing sodium polysulfides of stoichiometries Na2S3, Na2S4, and Na2S5 by the direct reaction of sodium and sulfur. The reaction is carried out in the furnace well of an inert−atmosphere glove box and features the slow addition of sulfur to molten sodium at temperatures ranging from 100–150°C at the start of the reaction to about 300°C at the end. Batches of 150–200 g of polysulfide product can be prepared with yields approaching 100% and a high purity.
Immmoglobulin E-rich plasma from patients from Papua New Guinea infected with Necator americanus has been used to probe an adult N. americanus cDNA library for the presence of hookworm allergens. Using this approach, one hookworm allergen has been identified as calreticulin, which was subsequently expressed in Escherichia coli. Little serological cross reactivity was seen between the recombinant calreticulins of this hookworm and its host. Prospective roles for hookworm calreticulin in the host-parasite relationship are discussed in depth.
Circular dichroism spectropolarimetry and X-ray scattering data, obtained using synchrotron radiation, can yield information about the secondary and tertiary structure of proteins in solution. These techniques have been used to analyse the architecture and shape of a complex of two proteins in solution. The crystal structures of two separate proteins, the C-terminal domain of Pex5p and SCP2, are available but their complex has not previously been structurally characterized. Circular dichroism spectropolarimetry indicated that complex formation requires little secondary structure rearrangement. X-ray scattering data fit an elongated irregular `shoe'-shaped particle of the complex of the two proteins, with dimensions of the order of 30 Å × 40 Å × 90 Å. Comparison with the known crystal structures suggests that this `shoe' shape requires a conformational change of the C-terminus of SCP2 to appropriately locate its peroxisomal targeting signal type-1 recognition motif into the binding pocket of the Pex5p receptor. Implications of the combined use of synchrotron-based circular dichroism spectropolarimetry and X-ray scattering in structural biology and proteomics are discussed.
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