Definition of protoporphyrin in English:
protoporphyrin
noun ˌprəʊtə(ʊ)ˈpɔːf(ɪ)rɪn
Chemistry Any of a group of fifteen isomeric porphyrins having the formula C₃₄H₃₄N₄O₄, in which the porphin nucleus has four methyl, two vinyl, and two propionic acid substituents; especially (more fully "protoporphyrin IX") the isomer which occurs widely in living organisms, mainly as haem (in which it is bonded to an iron atom).
Origin
1920s; earliest use found in Chemical Abstracts. From proto- + porphyrin, after German Protoporphyrin.
Definition of protoporphyrin in US English:
protoporphyrin
nounˌprəʊtə(ʊ)ˈpɔːf(ɪ)rɪn
Chemistry Any of a group of fifteen isomeric porphyrins having the formula C₃₄H₃₄N₄O₄, in which the porphin nucleus has four methyl, two vinyl, and two propionic acid substituents; especially (more fully "protoporphyrin IX") the isomer which occurs widely in living organisms, mainly as haem (in which it is bonded to an iron atom).
Origin
1920s; earliest use found in Chemical Abstracts. From proto- + porphyrin, after German Protoporphyrin.