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: ["Protein", "Chemical"].

Please return the output as a JSON object of the format: {"Chemical" : ["Dexamethasone", ...], "Protein" : ["BRCA-1", ...]}. 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:

Accurate quantum chemical energies for tetrapeptide conformations: why MP2 data with an insufficient basis set should be handled with caution.
High-level quantum chemical calculations have been carried out for biologically-relevant conformers of tetrapeptides. Our results indicate potential problems if the widely-applied MP2 approach is used in such situations with basis sets of insufficient size. Efficient alternatives are discussed.
{"Chemical": ["tetrapeptide", "tetrapeptides"], "Protein": []}