Protein structure | Primary | Secondary | Tertiary | Quaternary

hey everyone put back a mr. basics here let's talk about structure of protein so the proteins have a primary secondary tertiary and a quaternary structure let's talk about each of them primary structure of protein primary structure of protein is a linear sequence of amino acids present in a protein this linear sequence of amino acid is either written in a three letter or a one letter form now these amino acids are attached with each other by a peptide bond now the primary structure of protein is always written from the end terminal of the first amino acid

to the C terminal of the last amino acid the information of the primary structure protein can be obtained by sequencing the gene that encodes the protein this information can also be obtained by sequencing the protein itself secondary structure of protein now in the primary structure of protein the amino acids are linked by peptide bond and the peptide bond has an oxygen attached with a carbon and a nitrogen attached with the hydrogen both oxygen and hydrogen have the ability to form hydrogen bond and this results in folding of the peptide chain either an alpha helix or

neither a sheet let's talk about alpha helix alpha helix is the most common secondary structure of protein and the structure the protein attains a spiral shape such that the side chain of amino acid remains outwards the alpha helix is stabilized by hydrogen bonding this hydrogen bonding is formed between the hydrogen of nitrogen and the oxygen attached with the carbon individual hydrogen bonding are of course weak but collectively they are strong enough to stabilize the spiral structure all the peptide bond except the first and the last participate in the hydrogen bonding each turn of the helix

has three point six amino acids at a distance of 0.5 4 nanometers presence of amino acids like prolene can make the helix unstable and destruct the helix the beta sheet rena sheet is a second type of secondary structure of protein now in alpha helix the hydrogen bonding was between the same peptide chain while in me Rashid the hydrogen bond is formed between the two different polypeptide or the same polypeptide chain the beta sheet can be eating arranged in a parallel or antiparallel fashion tertiary structure of protein arrangement of protein in the three-dimensional space is the

tertiary structure of protein the tertiary structure will also have other bonds like disulfide bond hydrophobic interactions and ionic interactions quaternary structure of protein the protein having tertiary structure can further interact with other tertiary structure proteins to either form dimers trimers tetra Mars and so on the structure so form is called quaternary structure most of the proteins in the cell have the quaternary structure [Music]