( ( ( Certain kinds ) ( of ( catalysts ( found ( in ( living things ) ) ) ) ) ) ( ( are ( ( ( referred ( to ( as enzymes ) ) ) -- ) ( proteins ( that ( act ( to ( ( speed up ) ( ( chemical reactions ) ( that ( serve ( to ( fuel ( living things ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Certain) (NNS kinds)) (PP (IN of) (NP (NP (NNS catalysts)) (VP (VBN found) (PP (IN in) (NP (VBG living) (NNS things))))))) (VP (VBP are) (VP (VBN referred) (PP (TO to) (NP (QP (RB as) (CD enzymes)))) (: --) (NP (NP (NNS proteins)) (SBAR (WHNP (WDT that)) (S (VP (VBP act) (S (VP (TO to) (VP (VB speed) (PRT (RP up)) (NP (NP (NN chemical) (NNS reactions)) (SBAR (WHNP (WDT that)) (S (VP (VBP serve) (S (VP (TO to) (VP (VB fuel) (NP (VBG living) (NNS things)))))))))))))))))) (. .)))
Certain kinds of catalysts found in living things are referred to as enzymes -- proteins that act to speed up chemical reactions that serve to fuel living things.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (NNS catalysts)) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (VP (VBN found) (ADVP (RB inside)) (PP (IN of) (S (VP (VBG living) (NP (NNS things) (NNS enzymes))))))))))) (. .)))