R-Groups in Amino Acids
R-Group Sterics
Because of sterics, R-groups in amino acid chains face alternating directions (eg, east-west).
Functional groups will arrange themselves around the central atom to reduce the strain placed on the bonds by the sizes of attachments and by interactions between atoms.
To illustrate this, we show a stack of binders with an R group attached to the spine of each binder, and all the binders facing the same direction. After a few binders are stacked like this, the binders will start to slide off the top of the pile. So we redraw the stack of binders with the binders going in opposing directions, which stabilizes them. In this configuration, the R groups now face opposite directions, too.
R-Group Sterics
- R-groups face alternating directions (eg, east-west)
- Reduces strain