[arvin_infinity]

So looking at Haemoglobin structure, which bit of it is actually the


1)ligand
2)transition metal ion

Here is my attempt:


1)Haem + water/o2/co2/co+ globin
2)Fe 2+


+rep

[thegodofgod]

(Original post by arvin_infinity)
So looking at Haemoglobin structure, which bit of it is actually the


1)ligand
2)transition metal ion

Here is my attempt:


1)Haem + water/o2/co2/co+ globin
2)Fe 2+


+rep

From what I remember of the 'normal' (nothing associated onto the Hb molecule) haem group structure, the ligands are nitrogen atoms, and the transition metal ion is an Fe²⁺ ion.

When oxygen is associated onto a Hb molecule, oxygen is a monodentate ligand to the Fe²⁺ ion, and when carbon dioxide is associated onto a Hb molecule, one of the oxygen atoms from the carbon dioxide is a monodentate ligand to the Fe²⁺ ion.

[illusionz]

The ligand is the porphyrin ring, so Heme. The remaining two coordination sites are occupied by water initially, but one of water molecules is displaced by dioxygen or CO.

[arvin_infinity]

(Original post by illusionz)
The ligand is the porphyrin ring, so Heme. The remaining two coordination sites are occupied by water initially, but one of water molecules is displaced by dioxygen or CO.

So what happened to globin then!

[arvin_infinity]

(Original post by thegodofgod)
From what I remember of the 'normal' (nothing associated onto the Hb molecule) haem group structure, the ligands are nitrogen atoms, and the transition metal ion is an Fe²⁺ ion.

When oxygen is associated onto a Hb molecule, oxygen is a monodentate ligand to the Fe²⁺ ion, and when carbon dioxide is associated onto a Hb molecule, one of the oxygen atoms from the carbon dioxide is a monodentate ligand to the Fe²⁺ ion.

Hmm..so now am sure about the t. metal ion!
But still not so sure about the ligands!
I mean there are 3 types of different ligands right?

Also the shape is octahedral considering there are 6 coordinate bonds in there!?

[charco]

(Original post by arvin_infinity)
So what happened to globin then!

Globin is the name of the protein attached to the four haem groups.

Check this out... haemoglobin

[illusionz]

(Original post by arvin_infinity)
So what happened to globin then!

Globin is not a ligand, it's the family of proteins. The protein binds heme, which in turn binds oxygen

[illusionz]

(Original post by thegodofgod)
From what I remember of the 'normal' (nothing associated onto the Hb molecule) haem group structure, the ligands are nitrogen atoms, and the transition metal ion is an Fe²⁺ ion.

When oxygen is associated onto a Hb molecule, oxygen is a monodentate ligand to the Fe²⁺ ion, and when carbon dioxide is associated onto a Hb molecule, one of the oxygen atoms from the carbon dioxide is a monodentate ligand to the Fe²⁺ ion.

Just a note, you might not need to know this at A level but the act of binding the oxygen molecule to the Fe oxidises it to Fe³⁺

[thegodofgod]

(Original post by illusionz)
Just a note, you might not need to know this at A level but the act of binding the oxygen molecule to the Fe oxidises it to Fe³⁺

So is that an ionic bond instead of a dative covalent bond then (as I presume the oxygen somehow gets reduced to O^-)?

[charco]

(Original post by thegodofgod)
So is that an ionic bond instead of a dative covalent bond then (as I presume the oxygen somehow gets reduced to O^-)?

No it's a normal coordinate bond and the oxygen becomes the superoxide ion in the process...

... but you don't need this for A' level.

[thegodofgod]

(Original post by charco)
No it's a normal coordinate bond and the oxygen becomes the superoxide ion in the process...

... but you don't need this for A' level.

Isn't the O₂^- ion a free radical - so it must then react with another species?

Haemoglobin does some cool stuff

[arvin_infinity]

(Original post by charco)
Globin is the name of the protein attached to the four haem groups.

Check this out... haemoglobin

(Original post by illusionz)
Globin is not a ligand, it's the family of proteins. The protein binds heme, which in turn binds oxygen

Oh I seee..I only said that cuz I remember globin donates a pair of electrons to fe2+ so I thought thats a ligand!

(Original post by illusionz)
Just a note, you might not need to know this at A level but the act of binding the oxygen molecule to the Fe oxidises it to Fe³⁺

+rep
Thats a good one! my teacher kinda mentioned it too!