has role independent continuant ammonia cofactor ammonium QGZKDVFQNNGYKY-UHFFFAOYSA-O 18.03383 H4N InChI=1S/H3N/h1H3/p+1 [H][N+]([H])([H])[H] 18.03850 An onium cation obtained by protonation of ammonia. +1 nitrogen hydride onium cation monovalent inorganic cation Saccharomyces cerevisiae metabolite Escherichia coli metabolite human metabolite