( ( Each protein ) ( ( is ( ( made up ) ( of ( ( several ( nitrogen compounds ) ) ( called ( amino acids ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT Each) (NN protein)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NP (JJ several) (NN nitrogen) (NNS compounds)) (VP (VBN called) (NP (JJ amino) (NNS acids))))))) (. .)))
Each protein is made up of several nitrogen compounds called amino acids.
(ROOT (S (NP (DT A) (NN protein)) (VP (VBZ is) (NP (NP (DT an) (JJ organic) (NN compound)) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (NP (JJ small) (NNS molecules)) (VP (VBN called) (NP (JJ amino) (NNS acids)))))))) (. .)))