Task 2 – P3M2Structureand Function of HaemoglobinPrimaryStructure: This is haemoglobin at the simplest level, it is made up ofchains of amino acids, with peptide bonds separating each amino acid.
Itconsists of four polypeptide chains, two alpha (?) chains and two beta (?) chains.SecondaryStructure: The two types of secondary structure found in proteins arethe alpha-helix (?) or theBeta-pleated (?)sheet. These structures both involve polypeptide chains, however, in thisinstance they form different shapes, these are held together by weakintermolecular forces called hydrogen bonds. Hydrogen bonds can be foundbetween the N-H and C=O groups, giving it a more stable structure. TertiaryStructure: This is the main bonding which is involved in stabilising thestructure in each haemoglobin chain. The haem molecule is involved in thebending of the haemoglobin, creating the 3D structure of the chain.
Ashaemoglobin is a globular protein, this means that ball-like structures tend tobe formed, where the hydrophobic part is towards the centre and the hydrophilicpart is towards the edges, this means that they are water soluble. Quaternary Structure: These are proteins that contain more than one polypeptidechain which can be held together by hydrogen, ionic and disulfide bonds. Haemoglobincontains four polypeptide chains, and each of these contain a haem group(prosthetic group). Also, there is an iron ion (Fe²?) which is where the oxygen bindsdue to iron’s high affinity for oxygen. Haemoglobin can be found in the redblood cells in the circulatory system. How The Protein is Able to Maintainits Structure:Hydrophobic Interaction – These weak bonds stayinside of the 3D structure of haemoglobin, and they form between R groups,which only contain hydrogen and carbon.
These interactions are hydrophobic,meaning they repel water. These amino acids contain non-polar side chains,meaning they are not charged. Hydrophilic Interaction – These are found on theoutside of the 3D structure of haemoglobin, and they are hydrophilic, meaningthat they attract water.
These amino acids contain polar side chains, meaningthey are charged.Overall, this means that haemoglobin is water soluble. Disulfide Bridges – These are formed between twosulfur atoms found on two opposite cysteine amino acids, when this happens,each cysteine loses a H?.
These are exceptionally strong bonds and can only be broken by reducing agents,not by things like pH temperature. Hydrogen Bonds – These can form between an oxygenor a nitrogen atom and a hydrogen atom found on different amino acids. For thisto occur, the oxygen or nitrogen must have a lone pair of electrons in order toform a hydrogen bond. Then, the lone pair of electrons will be shared by theoxygen or nitrogen atom on one amino acid and the hydrogen atom on the theamino acid.
Ionic Bonds – These are formed betweenoppositely charged variable (R) groups on amino acids which contain acarboxylic acid (-COOH) group and an amine (-NH?) group. These bonds are stongerthan hydrogen bonds and can be broken by a change in temperature or pH. Function ofHaemoglobin:Haemoglobin is found in the red blood cells, where it carriedoxygen through the repiratory system and around the rest of the body. It is aglobular protein which shows a quaternary structure, and it also contains otherstructures such as haem groups and iron ions. This allows oxygen to bind to it,and this is possible because the iron ion give haemoglobin a high affinity foroxygen.
References: https://image.slidesharecdn.com/06-hbbyasif-161017032416/95/hemoglobin-structure-15-638.jpg?cb=1476674684Date Accessed: 16/01/18http://www.biotopics.co.uk/as/haemoglobinproteinstructure.htmlDate Accessed: 16/01/18 https://alevelnotes.com/Protein-Structure/61Date Accessed: 16/01/18 FYJMR Y YMFDTND DTFYI,7 RYURTUDMDHCVBCGRSYN DUYI OGU,FYM DTSTYNSHFCNGCJMRFM UMDETEDTYDETDE6UR7IIKRK8RRRRRRRRURR7IRIMR FMFYJMFYYMYEDTYDYSRYSYS5SYNHTCJGCGXGXHTTNGUGKVKVKVV