HEMERYTHRIN and HEMATIN.pptx solidarityy

HEMERYTHRIN and HEMATIN.pptx solidarityy

1. HEMERYTHRIN AND HEMATIN BIOINORGANIC CHEMISTRY RANJIT KUMAR MALIK CHEMISTRY DEPARTMENT 23CY4511

2. HEMERYTHRIN The basic structural fold of hemerythrin‐like proteins consists of an up‐and‐down four helix bundle with an overall right‐handed path. it is a non heme protien It act as a storage and transport of oxygen and found in invertebrates It contains 8 subunits and each subunits contain 113 amino acids and 2 Fe +2 it mainly binds oxygen reversibly 2

3. 3 TWO ACTIVE SITES IN HEMERYTHRIN ACTIVE SITES STRUCTURE OF DEOXYHEMERYTHRIN Each monomeric units contain an active sites which have two high spin ferrous ions[fe +2 ]. The ferrous ions are bridged together by hydroxyl group and two carboxyl groups make an asparate residue and a glutamate residue of the protein chain. One of the ferrous ion hexacoordinated with an octahedral geometry and other one pentacoordinated with a distorted triogonal bipyramidal geometry These two ions are satisfied by three and two imidazole nitrogen respectively from histidine residue of the protein chain.

4. 4 ACTIVE SITES STRUCTURE OF OXYHEMERYTHRIN One monomeric unit of hemerythrin binds to dioxygen. One dioxygen adds to the hemerythrin in an oxidative manner resulting in the formation of two Fe(III)centers and peroxide. The oxidative addition is followed by the shifting of proton from the bridged OH to the bound peroxide resulting in the formation of hyperoxo group This proton transfer result in the formation of single oxygen atom bridge in oxyhemorythrin .

5. Deoxy form 5 Oxyform 2Fe +2 present. The complex is mainly high spin. One Fe +2 has five coordination number and another have six. Deoxy form is mainly colourless . 2Fe +3 present. The complex is mainly low spin. Both fe +3 have six coordination number. Oxy form is coloured due to LMCT.

6. HEMATIN It is a dark bluish or brownish pigment containing iron in ferric state obtain by the oxidation of heme [1] . It do not have properties of oxygen transport. Here is a free heme group mainly present i,e heme without protein chain. 6

7. 7 MECHANISM: PR-Fe(II) +O 2 H 2 O PR-Fe(II) O O PR-Fe(II) O O +PR-Fe(II) PR-Fe (III) -O O-Fe(III) - PR (Per-oxo linkage) PR-Fe (III) -O O-Fe(III) - PR Cleavage 2 PR-Fe(IV) O 2PR-Fe(IV) O + PRFe (II) PR-Fe(III) O (III)Fe-PR Hematin   How does free Heme group react with dioxygen

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