In this video, we're going to talk more about the peptidoglycan structure. Peptidoglycan consists of repeating units of two different monosaccharides. These monosaccharides are linked to each other covalently by a special type of bond known as a beta-1,4-glycosidic linkage. The two monosaccharides are N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). These NAG and NAM subunits are repetitively linked together to create a long chain known as a glycan chain. So, the glycan chain is really just a sugar chain, made up of repeating units of NAG and NAM repetitively linked together.
If we take a look at the image on the left-hand side below, it shows an image representing peptidoglycan structure. It shows multiple glycan chains; each referred to as a glycan chain. We're displaying three glycan chains here, and each of these chains consists of repeating NAG and NAM subunits. Notice that the NAG subunits are in blue and the NAM subunits are in green. In addition to these glycan chains, there's also a four amino acid chain known as a tetrapeptide. Since 'tetra' is the prefix that means four, and these are amino acids, it forms a small peptide. This tetrapeptide is attached to each of the NAM molecules and is important for the cell wall structure to provide extra rigidity.
In the image below, in addition to these glycan chains, what links these glycan chains are tetrapeptide units, which are very important for linking adjacent glycan chains together. On the right-hand side image, it zooms into this specific region. Here you can see an N-acetylglucosamine molecule, which is the NAG subunit, and an N-acetylmuramic acid molecule, which is the NAM subunit. Notice that the NAG and NAM subunits are linked to each other via a bond known as a beta-1,4-glycosidic linkage, which links monosaccharides together. Branching off of the NAM subunit is a tetrapeptide. This tetrapeptide consists of four amino acids, and each of these circles represents an amino acid. This concludes our brief introduction to peptidoglycan structure, and we'll be able to get some practice applying these concepts as we move forward in our course. I'll see you all in our next video.
