How many {activating neurotransmitter} are to/by {DL-glutamic acid} ?
How many activating neurotransmitters are there in DL-glutamic acid?
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?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> ?sub .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P928> .
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} 

What is the number of activating neurotransmitters in the DL-glutamic acid?