( Proteins ( ( are ( ( chains ( -LRB- ( polymers -RRB- ) ) ) ( of ( amino acids ) ) ) ) . ) )
(ROOT (S (NP (NNPS Proteins)) (VP (VBP are) (NP (NP (NP (NNS chains)) (PRN (-LRB- -LRB-) (NP (NNP polymers)) (-RRB- -RRB-))) (PP (IN of) (NP (JJ amino) (NNS acids))))) (. .)))
Proteins are chains (polymers) of 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))))))))) (. .)))