( ( ( proteins - ) ( ( a ( long chain ) ) ( of ( ( amino acids ) ( ( linked end ) ( to ( end ( by ( peptide bonds ) ) ) ) ) ) ) ) ) ; )
(ROOT (NP (NP (NP (NNS proteins)) (: -) (NP (NP (DT a) (JJ long) (NN chain)) (PP (IN of) (NP (NP (JJ amino) (NNS acids)) (VP (VBN linked) (NP (NN end)) (S (VP (TO to) (VP (VB end) (PP (IN by) (NP (JJ peptide) (NNS bonds))))))))))) (: ;)))
proteins - a long chain of amino acids linked end to end by peptide bonds;
(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))))))))) (. .)))