proprietary amino acid

[paris 06]

what is "proprietary amino acid "?

[Raymott]

what is "proprietary amino acid "?

It's an artificial amino acid that has been manufactured by a certain company which has property rights over its use.
However, I notice on Google that the term is mostly used in the sense of "proprietary amino acid supplements." This means that the amino acids are natural, but their combination in the supplement is proprietary.
They are proprietary [amino acid supplements], not supplements of [proprietary amino acids].
(Hence the need for context.)