| Introduction | | | | the beta sheet, the tertiary structure is the folding of |
| When building large structures, one | | | | the polypeptide chains and quaternary structure is |
| must think of how to make sure the structure is long | | | | the association of sub units of protein into larger |
| lasting, neat and ready serve its purpose. In very | | | | ones. Hydrogen bonds are involved in the secondary, |
| large structures, using the example of buildings, | | | | tertiary and the quaternary structure of proteins. |
| builders build several columns in the ground floor and | | | | How do the amino acids become proteins? |
| triangle-like logs on the roof which do not interfere | | | | After the sequence of the amino |
| with the buildings' functionality as well as preventing | | | | acids are determined, the Alpha helix is formed which |
| the building from collapsing. Having a column right in | | | | is the formation of hydrogen bonds between the |
| the middle of a meeting room wouldn't be | | | | C=O and N−H groups of amino acids. Then the |
| appropriate; so where these assisting blocks are put | | | | Beta sheet comes into existence with the formation |
| would also be needed to be considered. The same | | | | of hydrogen bonds between different polypeptide |
| patterns are seen in proteins too where bonds form | | | | chains. The protein is already becoming a stable |
| at specific places in specific amounts to make the | | | | structure, with the hydrogen bonds forming at the |
| protein strong enough to cope with the jobs they | | | | right spots. Then the polypeptide chains start to fold |
| are doing. These bonds are called the Hydrogen | | | | according to where the hydrogen bonds were |
| bonds. | | | | formed in the secondary structure; the hydrogen |
| Hydrogen bonds are non-covalent | | | | bonds also play a role in helping the protein keep the |
| meaning they are created by the electrostatic | | | | shape of its tertiary structure. As the polypeptide |
| attractions between positive and negative charged | | | | chains fold, they require support in order to be kept |
| atoms and form spontaneously without the need for | | | | at the shape it has taken and again hydrogen bonds |
| enzyme catalysis (1). However they are quite weak | | | | provide it, working with other bonds this time, |
| so very little amount of energy is required to break | | | | including covalent bonds like disulphide bridges (3). |
| these bonds. This could be an advantage as well as | | | | Finally the quaternary structure exists only in proteins |
| being a disadvantage, even though structures bonded | | | | that contain more than one polypeptide. Hydrogen |
| by hydrogen bonds are not very strong, they are | | | | bonds are also found in the quaternary structure. |
| quite flexible which could be useful when the | | | | Conclusion |
| structure needs to change shape according to its | | | | As we can see hydrogen bonds |
| function. This is where proteins come in to play. | | | | play a very important role in keeping the shape of |
| Proteins are found everywhere in | | | | proteins. Depending on the primary structure, they |
| and between cells, doing so many jobs. They have a | | | | form at specific places and determine all the other |
| specific 3D shape which directly relates to its | | | | levels of organization of proteins. Without them the |
| function, so there is a lot of diversity in proteins but | | | | tertiary structure would be different meaning the |
| every single one does a different job and do not | | | | protein cannot bind and interact with the molecules it |
| interfere with each others'. | | | | needs to which would result in a malfunctioning |
| Hydrogen Bonds in Protein Structure | | | | protein. Hydrogen bonds could be likened to match |
| Proteins are synthesized in the | | | | sticks, you can break one easily but if you bring ten |
| cytoplasm of a cell when the codon of mRNA from | | | | of them together they become strong and more, |
| the nucleus binds with the anti-codon of tRNA which | | | | even stronger; and without functioning proteins we |
| results in the synthesis of amino acids, which are the | | | | wouldn't be alive! |
| base units of proteins. Proteins have four levels of | | | | (see: |
| organisation called the primary, secondary, tertiary | | | | References |
| and quaternary structure (2). The primary structure | | | | (1) Elliott, W. Elliott, D. 2005. Biochemistry and |
| relates to the sequence of the amino acids, the | | | | Molecular Biology 3rd Ed. pp10-12 and pp52-55 |
| secondary structure is formed by the alpha helix and | | | | (2) Snustad, P. Simmons, M. 2006. |