You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

New pockets in dengue virus 2 surface identified by molecular dynamics simulation. One of the factors limiting the search of new compounds based on the structure of target proteins involved in diseases is the limited amount of target structural information. Great advances in the search for lead compounds could be achieved to find new cavities in protein structures that are generated using well established computational chemistry tools. In the case of dengue, the discovery of pockets in the crystallographic structure of the E protein has contributed to the search for lead compounds aimed at interfering in conformational transitions involved in the pH-dependent fusion process. This is a complex mechanism triggered by the acid pH of the endosomes that leads to the initial changes in the E protein assembly at the virus surface. In the present work, an arrangement of three ectodomain portions of the E protein present on the surface of the mature dengue virus was studied through long all-atom molecular dynamics simulations with explicit solvent. In order to identify new pockets and to evaluate the influence of the acid pH on these pockets, the physiological neutral pH conditions and the acid pH of the endosomes that trigger the fusion process were modeled. Several pockets presenting pH-dependent characteristics were found in the contact regions between the chains. Pockets at the protein-protein interfaces induced by a monomer in another monomer were also found. Some of the pockets are good candidates for the design of lead compounds that could interfere in the rearrangements in E proteins along the fusion process contributing to the development of specific inhibitors of the dengue disease.
{"Chemical": []}