Editing Respiratory pigment (section)

== Comparing Respiratory Pigments ==
{| class="wikitable"
|+
! rowspan="2" |Metalloprotein
! colspan="2" |Globins
! rowspan="2" |Hemocyanin
! rowspan="2" |Hemerythrin
|-
!Hemoglobin{{efn|in the strict sense, for the tetrameric form}}
!Erythrocruorin and chlorocruorin
|-
! scope="row" |O<sub>2</sub> Binding Material
|Iron<ref name=":2">{{Cite book|url=https://www.worldcat.org/oclc/12558726|title=Respiratory pigments in animals: relation, structure-function|date=1985|publisher=Springer-Verlag|isbn=978-0-387-15629-3|editor-last=Lamy|editor-first=Jean|location=Berlin; New York|language=en|oclc=12558726|editor-last2=Truchot|editor-first2=J.-P|editor-last3=Gilles|editor-first3=R|editor-last4=International Union of Biological Sciences|editor-last5=Section of Comparative Physiology and Biochemistry|editor-last6=International Congress of Comparative Physiology and Biochemistry}}</ref>
|Iron<ref>{{Cite journal|last=Fox|first=H. Munro|date=1949|title=On Chlorocruorin and Haemoglobin|url=https://www.jstor.org/stable/82565|journal=Proceedings of the Royal Society of London. Series B, Biological Sciences|volume=136|issue=884|pages=378–388|doi=10.1098/rspb.1949.0031|jstor=82565|pmid=18143368|bibcode=1949RSPSB.136..378F|s2cid=6133526|issn=0080-4649|url-access=subscription}}</ref>
|Copper<ref name=":2" />
|Iron<ref name=":2" />
|-
! scope="row" |Location
|Intracellular<ref name=":1" />
|Extracellular<ref name=":3">{{Cite journal|last1=Fox|first1=Harold Munro|last2=Gardiner|first2=John Stanley|date=1932-09-01|title=The oxygen affinity of chlorocruorin|journal=Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character|volume=111|issue=772|pages=356–363|doi=10.1098/rspb.1932.0060|doi-access=free}}</ref>
|Extracellular<ref name=":1" />
|Intracellular<ref name=":1" />
|-
! scope="row" |Source Organism
|Almost all [[vertebrate]]s<ref name=":1" />
|{{plainlist|
* Annelids and arthropods
* Chlorocruorin: 4 families of marine [[polychaete]]s<ref>{{Cite journal|last1=Imai|first1=Kiyohiro|last2=Yoshikawa|first2=Shinya|date=1985|title=Oxygen-binding characteristics of Potamilla chlorocruorin|journal=European Journal of Biochemistry|language=en|volume=147|issue=3|pages=453–463|doi=10.1111/j.0014-2956.1985.00453.x|pmid=3979380|issn=1432-1033|doi-access=}}</ref>}}
|[[Arthropod]]a and [[Mollusca]]<ref name=":1" />
|
[[Sipuncula]], [[priapulida]], some [[brachiopod]]a, and a single [[annelid]] genus <ref name=":2" />
|-
! scope="row" |Oxygenated Color
|Bright red<ref name=":0" />
|{{plainlist|
* Erythrocruorin: Bright red
* Chlorocruorin: Green when diluted, red when concentrated <ref name=":3" />}}
|Blue<ref name=":0" />
|Violet<ref name=":0" />
|-
! scope="row" |Deoxygenated Color
|Crimson<ref name=":0" />
|{{plainlist|
* Erythrocruorin: Dark red
* Chlorocruorin: Green when diluted, brown-red when concentrated}}
|Colorless<ref name=":0" />
|Colorless<ref name=":0" />
|}
Hemoglobin, [[erythrocruorin]], and chlorocruorin are all [[globin]]s, iron-heme proteins with a common core. Their color comes from the absorption spectra of [[heme]] with Fe<sup>2+</sup>. Erythrocruorin and chlorocruorin are closely related giant globins found used by some invertebrates. Chlorocruorin has a special heme group, giving it different colors.

{{citation needed span|text=Any of various coloured conjugated proteins, such as hemoglobin, occur in living organisms and function in oxygen transfer in cellular respiration.|date=October 2019}}