/pawr"feuh rin/, n. Biochem.
a dark red, photosensitive pigment consisting of four pyrrole rings linked by single carbon atoms: a component of chlorophyll, heme, and vitamin B12.
[1905-10; < Gk porphýr(a) PURPLE + -IN2]

* * *

Any of a class of biologically important heterocyclic compounds of a characteristic chemical structure that includes four pyrrole groups (five-membered organic rings each containing a nitrogen atom) linked by additional carbon atoms to form a large flat ring.

As biological pigments, they and closely related molecules are responsible for many of the vivid colours in living organisms, where they often occur combined with metal ions and various substituents as coordination complexes (see compound). These include the magnesium-containing chlorophylls and the iron-containing heme group, a constituent (along with protein) of, e.g., hemoglobin, the cytochromes, and the enzyme catalase. In medicine, porphyrins are used in conjunction with light, often a laser beam, to induce reactions in the body against cancer and other diseases.

* * *

▪ biological pigment
      any of a class of water-soluble, nitrogenous biological pigments (biochromes), derivatives of which include the hemoproteins (porphyrins combined with metals and protein). Examples of hemoproteins are the green, photosynthetic chlorophylls of higher plants; the hemoglobins in the blood of many animals; the cytochromes, enzymes that occur in minute quantities in most cells and are involved in oxidative processes; and catalase, also a widely distributed enzyme that accelerates the breakdown of hydrogen peroxide.

      Evidence indicates that, in various animals, certain porphyrins may be involved in activating hormones from the pituitary gland of the brain, including those concerned with the period of sexual heat in certain female animals. Porphyrins in the integument (skin) of some mollusks and cnidarians are regarded as being photosensitive receptors of light.

* * *

Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • porphyrin — [pôr′fə rin] n. [< Gr porphyra, purple + IN1] any of a group of pyrrole derivatives, found in cytoplasm, that combine with iron and magnesium to form heme and chlorophyll, respectively …   English World dictionary

  • Porphyrin — Structure of porphine, the simplest porphyrin Heme group of hemoglobin. An …   Wikipedia

  • Porphyrin — Strukturformel des Porphyrin Gerüst mit Nummerierung. Strukturformel von Protoporphyrin IX. Porphyrine (nach griechisch πορφυρά, porphyrá, dem …   Deutsch Wikipedia

  • porphyrin — SYN: porphin. * * * por·phy·rin pȯr fə rən n any of various compounds with a structure that consists essentially of four pyrrole rings joined by four =CH groups esp one (as chlorophyll or hemoglobin) containing a central metal atom and usu.… …   Medical dictionary

  • porphyrin — porfirinas statusas T sritis chemija apibrėžtis Porfinui artimas junginys. atitikmenys: angl. porphyrin rus. порфирин …   Chemijos terminų aiškinamasis žodynas

  • Porphyrin à bec jaune — Porphyrospiza caerulescens Porphyrin …   Wikipédia en Français

  • porphyrin à bec jaune — geltonsnapis startinis kardinolas statusas T sritis zoologija | vardynas atitikmenys: lot. Passerina caerulescens; Porphyrospiza caerulescens angl. yellow billed blue finch rus. голубой овсянковый кардинал, m pranc. porphyrin à bec jaune, m… …   Paukščių pavadinimų žodynas

  • porphyrin à bec jaune — geltonsnapiai startiniai kardinolai statusas T sritis zoologija | vardynas atitikmenys: lot. Porphyrospiza angl. yellow billed blue finch rus. голубой овсянковый кардинал, m pranc. porphyrin à bec jaune, m ryšiai: platesnis terminas –… …   Paukščių pavadinimų žodynas

  • porphyrin — noun Etymology: International Scientific Vocabulary, from Greek porphyra purple Date: 1910 any of various compounds with a macrocyclic structure that consists essentially of four pyrrole rings joined by four =CH– groups; especially one (as… …   New Collegiate Dictionary

  • porphyrin — noun Any of a class of heterocyclic compounds containing four pyrrole rings arranged in a square; they are important in biochemistry in a form with a metal atom in the central cavity (hemoglobin with iron, chlorophyl …   Wiktionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”