( ( A protein ) ( ( is ( ( a ( long chain ) ) ( of ( ( smaller molecules ) ( called ( amino acids ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN protein)) (VP (VBZ is) (NP (NP (DT a) (JJ long) (NN chain)) (PP (IN of) (NP (NP (JJR smaller) (NNS molecules)) (VP (VBN called) (NP (JJ amino) (NNS acids))))))) (. .)))
A protein is a long chain of smaller molecules called amino acids.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN protein)) (VP (VBZ is) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (JJ amino) (NNS acids)) (VP (VBP are) (VP (VBN linked) (ADVP (RB together)) (PP (IN in) (NP (DT a) (JJ long) (NN chain))))))))) (. .)))