( ( In humans ) ( ( these ( two enzymes ) ) ( ( are ( linked ( in ( a ( single ( polypeptide chain ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN In) (NP (NNS humans))) (NP (DT these) (CD two) (NNS enzymes)) (VP (VBP are) (VP (VBN linked) (PP (IN in) (NP (DT a) (JJ single) (NN polypeptide) (NN chain))))) (. .)))
In humans these two enzymes are linked in a single polypeptide chain.
(ROOT (S (NP (NNP Insulin)) (VP (VBZ is) (VP (VBN made) (PRT (RP up)) (PP (IN of) (NP (CD two) (JJ polypeptide) (NNS chains))))) (. .)))