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:

A nonionic inhibitor with high specificity for the UDP-Gal donor binding site of human blood group B galactosyltransferase: design, synthesis, and characterization. 9-(5-O-α-D-galactopyranosyl)-D-arabinityl-1,3,7-trihydropurine-2,6,8-trione (1) was designed and synthesized as a nonionic inhibitor for the donor binding site of human blood group B galactosyltransferase (GTB). Enzymatic characterization showed 1 to be extremely specific, as the highly homologous human N-acetylgalactosaminyltransferase (GTA) is not inhibited. The binding epitope of 1 demonstrates a high involvement of the arabinityl linker, whereas the galactose residue is only making contact to the protein via its C-2 site, which is very important for the discrimination between galactose and N-acetylgalactosamine, the substrate transferred by GTA. The approach can generate highly specific glycosyltransferase inhibitors.
{"Chemical": ["N-acetylgalactosamine", "galactose", "N", "arabinityl", "9-(5-O-\u03b1-D-galactopyranosyl)-D-arabinityl-1,3,7-trihydropurine-2,6,8-trione", "UDP-Gal"]}