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Small-molecule probes that chemically tag targets by virtue of their enzymatic activities offer a means to focus system-wide experiments and provide functional information for entire families of proteins. Recent advances in the design and application of light-activated probes that target metalloproteases have created the opportunity to study this medically important family of enzymes in unprecedented detail.
There is a growing medical need for additional anti-angiogenic drugs. A new model of regenerative angiogenesis in the fin of adult zebrafish promises to accelerate discovery of genes and drugs related to angiogenesis.
The crystal structures of two chain-building megasynthases, the fatty acid synthases of mammals and fungi, have recently been reported. Although both are composed of modules derived from the discrete enzymes that catalyze bacterial fatty acid synthesis, the two synthases have dramatically different architectures.
Oxidation of cysteine residues is a well-described means of sensing oxidative stress. Analysis of a bacterial transcriptional repressor protein indicates that metal-catalyzed oxidation of histidine residues can provide oxidative stress control in a cysteine-independent fashion.
GPR30, a G-protein coupled receptor, is a recent addition to the family of receptors that bind to estrogens and antiestrogens. A new, selective compound for GPR30 has been developed to dissect the role of GPR30 in estrogen signaling.
The hypothesis of ubiquitous fluctuations in gene expression has spurred the development of general methods for tracking temporal changes in protein concentrations in individual cells. The determination of protein levels with single-molecule sensitivity represents a significant advancement in the monitoring of cellular behavior that is driven by gene expression.
The enzyme γ-humulene synthase normally generates a mixture of more than 50 sesquiterpene products from a single substrate. Targeted evolution allowed the design of new mutants with greatly enhanced product specificity. The results provide a model for the divergent evolution of enzyme specificity from ancestral proteins of promiscuous function.
Eukaryotic initiation factor (eIF) 4A plays an essential role in translation initiation on most eukaryotic mRNAs by unwinding their secondary structure to permit ribosomal attachment and scanning. The natural product hippuristanol selectively inhibited eIF4A- and eIF4A-dependent modes of translation initiation.
Square-planar, four-coordinate metal complexes strip peptides from the binding site of MHC class II molecules. Removal of peptides derived from self-antigens could prevent class II–dependent activation of self-reactive T cells in autoimmune diseases such as rheumatoid arthritis.
The modified tRNA base 2-thiouridine is required for many steps in translation. Surprisingly, the biosynthesis of this simple derivative requires a minimum of four sulfur transfer reactions involving seven proteins.
Using single-molecule biophysical studies in an ion channel, the protonation state of engineered basic amino acids was measured in real time, making it possible to calculate the pKas of the substituted residues and creating a unique, comprehensive dataset for theorists studying the effects of an electrostatic environment on integral membrane protein function.
Protein α-helices often terminate in recognizable helix-capping motifs. The origin of thermodynamic stability for one such motif is now well understood.
Bacteria are covered in sugars that facilitate the establishment of pathogenic or symbiotic relationships with other cells. Microarrays of carbohydrate-binding proteins now can provide quick snapshots of these sugar coats as they change during the bacterial life cycle and differ among bacterial strains.
Looked at from the outside of the cell, proteins are often hidden behind a forest of sugar chains. Using a sugar analog to introduce thiols onto the tips of the branches of this forest alters cell attachment and has unexpected consequences for cell differentiation.
Enzymes that catalyze the formation of (S)-allantoin from the product of the urate oxidase reaction have been identified. This finding answers the longstanding question of how living organisms produce a single enantiomer of allantoin.
