2Alecture+8

Although any one h bond is quite weak many bonds can

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Unformatted text preview: noring the R ­groups)… NH3+ end HO HO HO HO ! H! NCCNCCNCCNCCNCCNCCNCCNCCO-! H HO HO HO HO! + This backbone structure by itself ­ without the R groups ­ helps the protein fold into “secondary structures” ­ forming flat planes, or rigid cylinders. These planes and cylinders are stabilized by hydrogen bonds between the repea>ng N ­H and C=O groups in the backbone. The “backbone” is a very simple repea>ng structure… NCCNCCNCC 5 1/24/10 What’s a hydrogen bond? •  A hydrogen bond is sort of a baby polar bond, and sort of a way for two atoms to share a single H. For example: The N ­H and carbonyl (C=O) groups in a protein can H bond to each other to produce either flat sheets or rigid rods. Although any one H bond is quite weak, many bonds can collaborate to form a stable structure. HO HO HO HO ! H! NCCNCCNCCNCCNCCNCCNCCNCC! H HO HO HO HO! OH OH OH OH ! -OCCNCCNCCNCCNCCNCCNCCNCCNCCO! OH OH OH O H O! + The serpen>ne winding shown here will produce a “beta sheet”. Hydrogen bonds are very weak interac>ons ­ not at all like covalent bonds. But they can really add up… Figure 3.6 The Four Levels of Protein Structure Alpha helix These sheets, rods, and loops arrange themselves in a given posi>on in space that determines the structure of the ac>ve site. This ter>ary structure is very hard to predict from the protein’s sequence. Beta pleated sheet These rods and cyli...
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This note was uploaded on 06/13/2013 for the course BIS 2A taught by Professor Grossberg during the Winter '08 term at UC Davis.

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