Science Concentrates

Kinase-substrate partners nabbed

Efforts to dissect cellular signaling pathways should be aided by a new method for identifying the kinase enzyme that phosphorylates a given protein substrate. Kinase-substrate interactions tend to be transient and of low affinity, making them difficult to detect by standard methods for identifying protein-protein interactions. Instead, Kevan M. Shokat, Dustin J. Maly, and Jasmina A. Allen of the University of California, San Francisco, trap fleeting kinase-substrate interactions via a cross-linking reaction [J. Am. Chem. Soc., 126, 9160 (2004)]. To do so, they replace the threonine or serine that normally gets phosphorylated in the substrate with a reactive cysteine residue. When this mutant substrate interacts with its partner kinase in the presence of the active-site inhibitor 5´-3,4-phthaldialdehyde adenosine (shown), the inhibitor intermolecularly cross-links the substrate's cysteine to the kinase's active-site lysine. "The cross-linking reaction is robust and appears to be general for the identification of a number of serine/threonine kinases," Shokat and coworkers report. They are now using the method to identify novel kinase-substrate interactions.

Parallel polymerizations monitored by light scattering

A recently developed light-scattering technique has been found to be useful for high-throughput screening of parallel polymerization reactions. Last year, physics professor Wayne F. Reed of Tulane University reported and patented the technique, called simultaneous multiple sample light scattering (SMSLS), and his group has now applied it to in situ parallel polymerization monitoring [J. Comb. Chem., published online July 16, http:// dx.doi.org/10.1021/cc049909u]. SMSLS analysis of polymerization samples yields light-scattering signatures that indicate whether each reaction occurred, whether there was an initial lag period, and how long the reaction took. The data also help predict reaction rates, estimate average molecular masses of products, and identify mechanistic aspects of reactions. Other monitoring techniques provide different or more detailed information on polymerizations but have not yet been adapted for multiple simultaneous measurements, the researchers note. SMSLS can also be used to make parallel absolute molecular weight determinations and to monitor enzymatic degradation reactions and polymer aggregation processes, Reed says.

Selecting a nanowire's cross-section

In their efforts to grow arrays of nanowires for nanoscale device applications, scientists have learned how to control the position, composition, and dimensions of the nanowires. Now, using a simple trick, researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory have demonstrated how to control another crucial parameter--the crystallographic growth direction, which determines the nanowire's cross-section [Nat. Mater., 3, 524 (2004)]. The trick is selecting the appropriate substrate for the kind of nanowires you want, says chemist Peidong Yang, who led the team. For example, when Yang and coworkers grow gallium nitride nanowires on a lithium aluminum oxide (-LiAlO₂) surface that has twofold symmetry, the nanowire cross-section is an isosceles triangle. When the nanowires are grown on a magnesium oxide surface having threefold symmetry, the wires sport hexagonal cross-sections. The Berkeley team also has shown that the two types of GaN nanowires emit light at different energies. This new level of control in the growth of nanowires may allow scientists to tune other material properties, aiding the development of new nanotechnologies.

Gene links inflammation and cancer

In their efforts to grow arrays of nanowires for nanoscale device applications, scientists have learned how to control the position, composition, and dimensions of the nanowires. Now, using a simple trick, researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory have demonstrated how to control another crucial parameter--the crystallographic growth direction, which determines the nanowire's cross-section [Nat. Mater., 3, 524 (2004)]. The trick is selecting the appropriate substrate for the kind of nanowires you want, says chemist Peidong Yang, who led the team. For example, when Yang and coworkers grow gallium nitride nanowires on a lithium aluminum oxide (-LiAlO₂) surface that has twofold symmetry, the nanowire cross-section is an isosceles triangle. When the nanowires are grown on a magnesium oxide surface having threefold symmetry, the wires sport hexagonal cross-sections. The Berkeley team also has shown that the two types of GaN nanowires emit light at different energies. This new level of control in the growth of nanowires may allow scientists to tune other material properties, aiding the development of new nanotechnologies.

Royal Society journal archive: Just £50 in U.K.

Thanks to financial backing from a U.K. educational body, the Royal Society of Chemistry is making its digital journal archive available to British universities for a one-time fee of just £50 (about $91) per institution. The archive contains more than 200,000 articles dating from 1841 through 1996. The material is drawn from such journals as Chemical Communications, Dalton Transactions, Faraday Discussions, and The Analyst. The Joint Information Systems Committee, a major education funding group that promotes the use of information and communications technology, has licensed the archive content in perpetuity on behalf of U.K. universities. Without the committee's support, the material would have cost the universities £25,000 each (about $45,500).