Converse of object

• call: Haem is one of a group of similar compounds called porphyrins.

• secrete: This gland secretes porphyrins ( red tears ) in response to stress.

Preposition: in

• synovium: Fluorescence measurements performed on the tissue specimens ex vivo showed the predominant accumulation of porphyrins in the synovium of the inflamed joints.

Modifies a noun

• ring: In the first case, the ring is orientated parallel to the porphyrin ring system of haem.

• metabolism: Some differences between pro-drugs were relatively small, but might be magnified in tumors, due to their enhanced porphyrin metabolism.

• biosynthesis: The homologues of the enzymes of the porphyrin biosynthesis pathway are found in different kingdoms of living organisms.

• dimer: Inclusion of C60 into an adjustable porphyrin dimer generated by dynamic disulfide chemistry.

• trimer: This confirms that the porphyrin trimer has exactly the right size to bind the exo product.

• heptamer: The synthetic porphyrin heptamer is potentially an exciting candidate for use in solar cells.

Noun used with modifier

• iron: The research study is focused on an unknown iron porphyrin compound.