Biochemistry 2280A Study Guide - Midterm Guide: Fibroin, Alpha Helix, Coiled Coil
Biochemistry 2280 – Midterm
Protein Structure
Understand peptides
- small number of joined residues
- polypeptides are many of them
- one end of peptide has a free amino group (N-terminal)
- the other has a free carboxyl group (C-terminal)
- additional amino acids are added to the C terminal; peptides are written N-terminal first
- 5 N-C-C-N-C-C-N-C-C 3
- side chains project from this backbone off of the carbons
Distinguish between primary and secondary protein structure
primary
• simply the sequence of residues making up the protein
• involves only the covalent bonds linking residues together
• the minimum size is about 50 residues; smaller than this are just peptides
• the largest protein so far discovered has 30,000 residues
• average molecular weight of a residue is about 110 Da
secondary
• local folding pattern of the backbone
• stabilized by hydrogen bonds
- between backbone N-H and C=O groups
• most common forms are alpha helix and beta sheets
- also some like loops, helices, and irregular conformations
• silk fibroin consists of mostly beta sheets
• keratin has lots of alpha structures (makes up hair)
• most proteins have both alpha and beta structures; plus other less
regular structure
• primary sequence determines the type of structure formed
Describe the characteristics of an alpha helix and beta sheet
alpha helix
• coil string arrangement
find more resources at oneclass.com
find more resources at oneclass.com