Kinetic analysis of the cleavage of human protease-activated receptor-1/2/3 and 4 using quenched-fluorescent peptide substrates

Protease-activated receptors [PARs] are a family of G-protein-coupled seven-transmembrane domain receptors that are activated by proteolytic cleavage of their amino-terminal exodomain. To characterize the cleavage rate of human PAR-1 / 2 / 3 and 4 by trypsin and thrombin, four synthetic quenched-fluorescent peptide substrates have been synthesized. Each substrate consisted of a ten-residue peptide spanning the receptor activation cleavage site and using progress-curve kinetics, k(cat)/K-m values were determined.

Isolation and preliminary biological assessment of AADGAPLIRFamide and SVPGVLRFamide from Caenorhabditis elegans

To date, 9 FMRFamide-related peptides (FaRPs) have been structurally characterised from Caenorhabditis elegans. Radioimmunometrical screening of an ethanolic extract of C. elegans revealed the presence of two additional FaRPs that were purified by reverse-phase HPLC and subjected to Edman degradation analysis and gas-phase sequencing. Unequivocal primary structures for the two FaRPs were determined as Ala-Ala-Asp-Gly-Ala-Pro-Leu-Ile-Arg-Phe-NH2 and Ser-Val-Pro-Gly-Val-Leu-Arg-Phe-NH2. Using MALDI-TOF mass. spectrometry, the molecular masses of the peptides were found to be 1032 Da (MH) and 875 Da (MH)(+), respectively. Two copies of AADGAPLIRFamide are predicted to be encoded on the precursor gene termed flp-13, while one copy of SVPGVLRFamide is located on flp-18. Synthetic replicates of the peptides were tested on Ascaris suum somatic muscle to assess bioactivity. ADDGAPLIRFamide had inhibitory effects on A. suum muscle strips, which occurred over a range of concentrations from a threshold for activity of 10 nM to 10 muM. SVPGVLRFamide was excitatory on A. suum somatic musculature from a threshold concentration for activity of 1 nM to 10 muM. The inhibitory and excitatory effects of AADGAPLIRFamide and SVPGVLRFamide, respectively, were the same for dorsal and ventral muscle strips as well as innervated and denervated preparations, suggesting that these physiological effects are not nerve cord dependent. Addition of ADDGAPLIRFamide (10 muM) to muscle strips preincubated in high-K+ and -Ca2+-free medium resulted in a normal inhibitory response. Peptide addition to muscle strips preincubated in Cl--free medium showed no inhibitory response, suggesting that the inhibitory response of the peptide may be chloride mediated. A normal excitatory response was noted following the addition of 10 muM SVPGVLRFamide to muscle strips preincubated in high-K+, Ca2+- and Cl--free media. (C) 2001 Academic Press.

Female reproductive biology of two sympatric incirrate octopod species, Adelieledone polymorpha (Robson 1930) and Pareledone turqueti (Joubin 1905) (Cephalopoda : Octopodidae), from South Georgia

The reproductive biology of two species of endemic Southern Ocean octopods was investigated around the sub-Antarctic islands of South Georgia and Shag Rocks. The females of both the species produce few, large eggs. This appears to be governed by phylogenetic constraint. No evidence was found for ontogenetic migration or seasonality associated with gonad maturation. Based on oocyte length frequency distributions and observations of oocyte development within the ovary, it is possible that both species could have either a single or multiple-batch spawning strategy. Pareledone turqueti ovaries contained fewer larger oocytes than those of Adefieledone polymorpha, which may help to reduce competition for resources immediately after hatching.

One-pot multistep synthetic strategies for the production of fenpropimorph using an ionic liquid solvent

The one-pot synthesis of the fungicide fenpropimorph has been achieved using two different synthetic strategies in an ionic liquid. The first pathway consists of a Heck coupling followed by reductive amination; the second pathway consists of an aldol condensation followed by hydrogenation/reductive amination. Homogeneous and heterogeneous palladium catalysts have been utilised in the ionic liquid to provide a catalyst/solvent system that is suitable for recycling and process optimisation.

A highly efficient synthetic procedure for deuteriating imidazoles and imidazolium salts

Both substituted imidazoles and 1,3-dialkylimidazolium salts can be fully deuteriated on the heterocyclic ring using D2O over heterogeneous Pd catalysts: deuteriated 1-alkyl-3-methylimidazolium chloride and hexafluorophosphate ionic liquids can also be prepared in good yields utilising readily available and relatively low cost sources of deuterium.

Chemoenzymatic synthesis of the trans-dihydrodiol isomers of monosubstituted benzenes via anti-benzene dioxides

Enantiopure cis-2,3-dihydrodiols, available from dioxygenase-catalysed cis-dihydroxylation of monosubstituted benzene substrates, have been used as synthetic precursors of the corresponding trans-3,4-dihydrodiols. The six-step chemoenzymatic route from cis-dihydrodiol precursors, involving acetonide, tetraol, dibromodiacetate and diepoxide intermediates, and substitution of vinyl bromide and iodide atoms, has been used in the synthesis of ten trans-dihydrododiol derivatives of substituted benzenes. The general applicability of the method has been demonstrated by its use in the synthesis of both enantiomers of the trans-1,2- and 3,4-dihydrodiol derivatives of toluene.

What Darwin Disturbed: The Biology that Might have been.

Uses counterfactual history to argue that Darwin had a unique impact on the development of moern biology.

IQ motif selectivity in human IQGAP1: binding of myosin essential light chain and S100B.

IQGAPs are cytoskeletal scaffolding proteins which link signalling pathways to the reorganisation of actin and microtubules. Human IQGAP1 has four IQ motifs each of which binds to calmodulin. The same region has been implicated in binding to two calmodulin-like proteins, the myosin essential light chain Mlc1sa and the calcium and zinc ion binding protein S100B. Using synthetic peptides corresponding to the four IQ motifs of human IQGAP1, we showed by native gel electrophoresis that only the first IQ motif interacts with Mlc1sa. This IQ motif, and also the fourth, interacts with the budding yeast myosin essential light chain Mlc1p. The first and second IQ motifs interact with S100B in the presence of calcium ions. This clearly establishes that S100B can interact with its targets through IQ motifs in addition to interacting via previously reported sequences. These results are discussed in terms of the function of IQGAP1 and IQ motif recognition.

New advances in radiation biology.

Current understanding of risk associated with low-dose radiation exposure has for many years been embedded in the linear-no-threshold (LNT) approach, based on simple extrapolation from the Japanese atomic bomb survivors. Radiation biology research has supported the LNT approach although much of this has been limited to relatively high-dose studies. Recently, with new advances for studying effects of low-dose exposure in experimental models and advances in molecular and cellular biology, a range of new effects of biological responses to radiation has been observed. These include genomic instability, adaptive responses and bystander effects. Most have one feature in common in that they are observed at low doses and suggest significant non-linear responses. These new observations pose a significant challenge to our understanding of low-dose exposure and require further study to elucidate mechanisms and determine their relevance.

Ionic liquids via reaction of the zwitterionic 1,3-dimethylimidazolium-2-carboxylate with protic acids. Overcoming synthetic limitations and establishing new halide free protocols for the formation of ILs

The previously reported preparation of 1,3-dimethylimidazolium salts by the reaction of 1,3-dialkylimidazolium-2-carboxylate zwitterions with protic acids has been reinvestigated in detail, leading to the identification of two competing reactions: isomerisation and decarboxylation. The ability to control both pathways allows this methodology to be used as an effective, green, waste-free approach to readily prepare a wide range of ionic liquids in high yields. Additionally, this reaction protocol opens new possibilities in the formation of other imidazolium salts, whose syntheses were previously either very expensive (due to ion exchange protocols involving metals like Ag) or difficult to achieve (due to multiple extractions and large quantities of hard to remove inorganic by-products).