A generic scaffold for conversion of peptide ligands into homogenous biosensors.

Numerous peptide ligands including protease recognition sequences, peptides mediating protein-protein interactions, peptide epitopes of antibodies and mimotopes are available which bind molecules of interest. However, there is currently no facile method for the incorporation of these peptides into homogenous detection systems. We present a generalizable method for the incorporation of such peptides into a novel fusion protein framework comprising an enzyme and its inhibitor. The incorporated peptide functions as an allosteric hinge, linking enzyme to its inhibitor. Upon interaction with its cognate analyte, the peptide mediates dissociation of the inhibitor from the enzyme, and facilitates one-step signal generation. Likewise, cleavage of the peptide by a specific protease also causes enzyme-inhibitor dissociation, leading to signal generation. Using the ß-lactamase Tem1 and its inhibitor protein as a model scaffold, we show both specific and sensitive (between low nanomolar and mid-picomolar) colorimetric detection of proteases and antibodies within minutes in a homogenous one-step reaction visible to the naked eye. The same scaffold affords in vivo detection of antibody binding and protease function by linking activity to a selectable phenotype in E. coli.

Biochemistry of envenomation.

Venoms and toxins are of significant interest due to their ability to cause a wide range of pathophysiological conditions that can potentially result in death. Despite their wide distribution among plants and animals, the biochemical pathways associated with these pathogenic agents remain largely unexplored. Impoverished and underdeveloped regions appear especially susceptible to increased incidence and severity due to poor socioeconomic conditions and lack of appropriate medical treatment infrastructure. To facilitate better management and treatment of envenomation victims, it is essential that the biochemical mechanisms of their action be elucidated. This review aims to characterize downstream envenomation mechanisms by addressing the major neuro-, cardio-, and hemotoxins as well as ion-channel toxins. Because of their use in folk and traditional medicine, the biochemistry behind venom therapy and possible implications on conventional medicine will also be addressed.