Haemoglobin Structure fourchained protein oxygen carrying ability dependant

Haemoglobin Structure • four-chained protein • oxygen carrying ability • dependant on Hb structure

Haemoglobin Structure To grossly over-simplify l l Genes code for protein production A “bad” gene makes a “bad” protein A missing gene makes no protein Problems in controlling DNA sequences occur

Haemoglobin Structure two alpha globin genes on chromosome 16 l each cell has two chromosomes 16 l a total of four alpha globin genes exist in each cell. l one beta globin gene on chromosome 11 l each cell has two chromosomes 11 l a total of two beta globin genes exist in each cell. l There also one gamma and one delta globin genes on chromosome 11

Haemoglobin Structure Neutral amino acid Poisitive amino acid Negative amino acid

Haemoglobin Structure Primary Structure • white represents areas of no charge • red represents areas of positive charge • green represents areas of negative charge

Haemoglobin Structure Secondary Structure The amino acid chain forms into a helix

Haemoglobin Structure Tertiary Structure The amino acid helix forms folds

Haemoglobin Structure Quaternary Structure The folded amino acid helices group together Non protein moities attach

Haemoglobin Structure Haem has a tetra-pyrrole ring structure containing a central iron atom Each globin chain of haemoglobin has a haem unit attached The haem is embedded deep in the hydrophobic part of the molecule

Haemoglobin Structure A protein with four amino-acid chains: • Two pairs of two like chains • Two alpha a (or Two epsilon e in fetal life) and • Two non alpha (b or g or d) • Each chain has a haem group attached

Haemoglobin Structure Hydprohilic exterior - charged Hydrophobic interior - neutral (haem pocket) • Poisonous - hence contained in red cells • Binds oxygen in high concentrations of O 2 • Releases it in low concentrations of O 2

Haemoglobin Structure Note that the molecule is smaller once it is oxygenated

Haemoglobin Structure Haem Synthesis l l l Very complex biochemical pathways Mishaps in haem production cause the porphyrias and iron deficiency anaemia We shall not consider the details here

Haemoglobin Structure l l The Hb molecule is a dynamic one The inside hydrophobic, outside hydrophilic It shrinks and expands as it functions A stray + or - charge will hinder the above The Hb molecule ‘s function is dependant on it’s structure

To summarise l l l a genes make a chains b genes make b chains haem attaches to the chains form a tetramer - haemoglobin is a dynamic structure carrying O 2