Mitsubishi Chemical Corporation

About: Mitsubishi Chemical Corporation is a company organization based out in Iwaki, Japan. It is known for research contribution in the topics: Layer (electronics) & Catalysis. The organization has 5345 authors who have published 4016 publications receiving 79378 citations.

Control of protein-ligand recognition using a stimuli-responsive polymer

Abstract: Stimuli-responsive polymers exhibit reversible phase changes in response to changes in environmental factors such as pH or temperature. Conjugating such polymers to antibodies and proteins provides molecular systems for applications such as affinity separations, immunoassays and enzyme recovery and recycling. Here we show that conjugating a temperature-sensitive polymer to a genetically engineered site on a protein allows the protein's ligand binding affinity to be controlled. We synthesized a mutant of the protein streptavidin to enable site-specific conjugation of the responsive polymer near the protein's binding site. Normal binding of biotin to the modified protein occurs below 32 degrees C, whereas above this temperature the polymer collapses and blocks binding. The collapse of the polymer and thus the enabling and disabling of binding, is reversible. Such environmentally triggered control of binding may find many applications in biotechnology and biomedicine, such as the control of enzyme reaction rates and of biosensor activity, and the controlled release of drugs.

Telomerase activation by hTRT in human normal fibroblasts and hepatocellular carcinomas.

Abstract: Telomerase is a specialized type of reverse transcriptase which catalyzes the synthesis and extension of telomeric DNA (for review, see ref.1). This enzyme is highly active in most cancer cells, but is inactive in most somatic cells2. This striking observation led to the suggestion that telomerase might be important for the continued growth3 or progression4 of cancer cells. However, little is known about the molecular mechanism of telomerase activation in cancer cells. Human telomerase reverse transcriptase (hTRT) has recently been identified as a putative human telomerase catalytic subunit5,6. We transfected the gene encoding hTRT into telomerase-negative human normal fibroblast cells and demonstrated that expression of wild-type hTRT induces telomerase activity, whereas hTRT mutants containing mutations in regions conserved among other reverse transcriptases did not. Hepatocellular carcinoma (2O samples) and non-cancerous liver tissues (19 samples) were examined for telomerase activity and expression of hTRT, the human telomerase RNA component (hTR; encoded by TER)7 and the human telomerase-associated protein (HTLP1; encoded by 7EP7)8,9. A significant correlation between hTRT expression and telomerase activity was observed. These results indicate that the hTRT protein is the catalytic subunit of human telomerase, and that it plays a key role in the activation of telomerase in cancer cells.