This study creates a device where the DNA is electronically integrated to serve as both the biological target and electrical transducer in a CNT–DNA–CNT device. We detect DNA binding and methylation by the methyltransferase M.SssI at the single molecule level. We demonstrate sequence-specific, reversible binding of M.SssI and protein-catalyzed methylation that alters the protein-binding affinity of the device. This device, which relies on the exquisite electrical sensitivity of DNA, represents a unique route for the specific, single molecule detection of enzymatic activity.

BACKGROUND Pyropia yezoensis, rich in porphyran, is a medicine‐edible red alga. In the present study, the physicochemical characteristics, conformational states and antitumor activities of a novel porphyran extracted from the high‐yield algal strain Pyropia yezoensis Chonsoo2 and its two degraded derivatives by gamma irradiation were investigated. RESULTS Pyropia yezoensis porphyran is a water‐soluble, triple‐helical sulfated hetero‐galactopyranose, named PYP. PYP was degraded by gamma irradiation at 20 kGy and 50 kGy, giving two low molecular weight derivatives comprising PYP‐20 and PYP‐50, respectively. PYP with a higher molecular weight has a solution conformation different from PYP‐20 and PYP‐50. Three porphyrans had no toxicity in normal human liver cells (HL‐7702) and showed antitumor effects on Hep3B, HeLa and MDA‐MB‐231. They had better antitumor against HeLa cells, exhibiting a similar inhibition ratio compared to 5‐fluorouracil, with PYP especially exhibiting a higher inhibition ratio than 5‐fluorouracil. With respect to HeLa cells, the different antitumor activities might be related to porphyran molecular weight and solution conformation. Furthermore, the HeLa cell cycle was blocked in the G2/M phase after PYP treatment, leading to cell proliferation inhibition. The induction of cell cycle arrest was related to the changes in the expression of p21, p53, Cyclin B1 and cyclin‐dependent kinase 1. CONCLUSION Pyropia yezoensis porphyran, as applied to medicine and functional food, could potentially be used as a non‐toxic natural adjuvant in cancer therapy. © 2019 Society of Chemical Industry

Olfactory receptors are ectopically expressed (exORs) in more than 16 different tissues. Studying the role of exORs is hindered by the lack of known ligands that activate these receptors. Of particular interest are exORs in the colon, the section of the gastrointestinal tract with the greatest diversity of microbiota where ORs may be participating in host–microbiome communication. Here, we leverage a G-protein-coupled receptor (GPCR)-based yeast sensor strain to generate sensors for seven ORs highly expressed in the colon. We screen the seven colon ORs against 57 chemicals likely to bind ORs in olfactory tissue. We successfully deorphanize two colon exORs for the first time, OR2T4 and OR10S1, and find alternative ligands for OR2A7. The same OR deorphanization workflow can be applied to the deorphanization of other ORs and GPCRs in general. Identification of ligands for OR2T4, OR10S1, and OR2A7 will enable the study of these ORs in the colon. Additionally, the colon OR-based sensors will enable the elucidation of endogenous colon metabolites that activate these receptors. Finally, deorphanization of OR2T4 and OR10S1 supports studies of the neuroscience of olfaction.