 So fibrous proteins are super important, but I have to confess I'm biased. I'm on the life science side of things So let's head on to talk about water soluble proteins we have Beta sheets forget about that small helix. It's almost entirely beta sheets You're gonna need to get used to this that Definitions are not perfect or strict when it comes to real proteins We have proteins that are almost entirely alpha helical and we have proteins that are a mix of helices and sheets And I'm gonna start going through these classes in detail and starting with beta sheets in a second But before doing this, I'm gonna need to Tell a little about a nomenclature. These are water soluble, but I also call them globular proteins globular The reason for that is mostly historical Some of the very first faults not just some of the very first faults we determined were this hemoglobin And then it's sibling myoglobin hemoglobin is for units and myoglobin is just one But the units are very similar and that unit is called a globin fold our globin and so globin and globular That nomenclature kind of stuck So the globin globin fold was the poster child for water soluble proteins And today we've just extended that so all globular proteins are water soluble You can think of them as roughly spherical and Globe-like, but even that is not true many of them are but not all you will have things that are water soluble But are quite extended For all of these you will also frequently see various cartoon representations. I and At least if you have multiple pens and everything I occasionally like to say color helices red and sheets blue At least if you have colors, that's not always going to work Even that type of structure can get very complicated if you have lots of helices and sheets So occasionally we will use these even simpler Representations you can use a circles and triangles that's that's great because it's going to work even if you're black and white There was a day when there were no color printers And then you somehow just draw lines between them to schematically show how they're connected because again Remember the previous slide when you have very large structures It can be difficult to make sense of them But by drawing this schematically just a secondary structure units we can stress the important parts for instance Are your beta sheets parallel or anti parallel? Is there a helix or a sheet there? Don't worry about the specific length is it helix sheet helix sheet helix sheet Or are the helices in one sequence and then you get the sheets you probably get the idea But before we look at the really complicated mixtures Let's start by looking at some pure beta sheet globular proteins