MCB 250 1st Edition Lecture 7Outline of Current Lecture 1. Beta Strand2. Antiparallel vs parallel3. Backbone structureCurrent Lecture1. Beta strand- Part of the protein that is extended- 2 beta strands come together to form a beta sheet and can form H bonds btwn backbone units. Carbonyl group on one amino group and one amino group. The H bondshold the strands together- 2ndary structure (beta strand) but beta strands come together to make a beta sheet.2. Antiparallel vs parallel- Antiparallel: N-terminus one direction, another one is N- terminus to C-terminus in another direction- Backbone units hydrogen bond fulfill: the properties of the sheets are defined by the R goups. Half of the R groups stick up, Half of the R groups stick down. Thus one half of thebeta sheet side can be hydrophobic vs hydrophilic.- Periodicity of Hydrophobic R groups to make the beta sheet have one side hydrophobic and hydrophilic—Every other one. o Periodicity for alpha helix is 3.5- Very stable structure because all H bonds line up evenly and are straight- Parallel beta plated sheets: not as stable because H bonds are crooked. They’re still there, but not as strong.- Not all proteins are either in alpha or beta. Theres another structure to get to one from another: have turns/loops- Hairpin loop: not alpha or beta – does have secondary structure that’s not so defined. 3. BackboneThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- All backbone H bonding donors and acceptors are satisfied. They don’t need to interact with water and they can form hydrophobic structures depending on R groups to satisfy the hydrogen
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