( ( ( A ( structural protein ) ) ( consisting ( of ( ( two pairs ) ( of ( polypeptide chains ) ) ) ) ) ) . )
(ROOT (NP (NP (DT A) (JJ structural) (NN protein)) (VP (VBG consisting) (PP (IN of) (NP (NP (CD two) (NNS pairs)) (PP (IN of) (NP (JJ polypeptide) (NNS chains)))))) (. .)))
A structural protein consisting of two pairs of polypeptide chains.
(ROOT (S (NP (NNP Insulin)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (CD two) (JJ polypeptide) (NNS chains))))) (. .)))