Proteins-Higher Orders of structure Flashcards
a-helix
H bonds nearby. Between amide and carbonyl groups.
Disrupted by proline, bulky, like charges
3.6 per turn, 5.4 ang. 6 ang diameter
b-sheet
H bonds NOT nearby.
Parallel (bent,weak)
Antiparallel (straight H bonds, stronger)
Random coil
Irregular arrangement of polypeptide chain
Strong helix formers
Ala and Val
Helix breakers
Pro and Gly
B-turns
180 degrees over 4 AAs.
H bind from carbonyl oxygen to amide proton 3 residues down.
Proline forces turns, glycine present at position 3 often
Domain
Sufficient to perform a chemical or physical task. Tertiary structure
Tertiary and Quarternary structure stabilized by
Hydrophobic, hydrophilic, salt bridges, hydrogen bonds, disulfide bonds
X-ray crystallography
Determine secondary and tertiary structure.
Pros: no size limit
Cons: difficult for membrane proteins, can’t see hydrogen’s
NMR
Determine secondary and tertiary structures.
Pros: can see many hydrogen’s and don’t have to crystallize.
Cons: difficult for insoluble proteins, works best with small proteins
Endosome -lysosomes pathway
Degrades extracellular and surface proteins
Uniquitin-proteasome pathway
Degrades proteins from cytoplasm, nucleus, and ER
Collagen
Fibrous in ECM, holds cells together, provides thermal stability and strength. Adhesion.
Gly-X-Y
Hydroxypro and Lys occur post translation
Adds hydroxyl groups to Pro and Lys in collagen
Metal containing enzymes, happens post translationally
Facilitates intrachain H bonds and stabilizes
Lysyl Oxidase
Catalyze formation of covalent cross links between collagen and elastin. Uses Cu2+
A-ketoglutarate,O2, Fe2+, ascorbate (vitamin c)
Required to add hydroxyl groups to collagen.
Ascorbic Acid deficiency
Scurvy. Formation of stable triple helix in collagen is I,paired. Bruise like discolorations, gum and teeth problems
Cu2+ deficiency
Menkes Disease
Ehlers-Danlos syndrome
Heterogenous group of connective tissue disorders from heritable defects in metabolism of fibrillar collagen molecules
Osteogenesis imperfecta
Collagen type 1. Brittle bones
Elastin.
Fibrous. lungs, arteries, ligaments, skin, and bladder.
Help blood flow in arteries and abundant in large vessels such as aorta
Elastin cross links
Tropoelastin is basic soluble unit.
Formed between amino groups of side chains and catalyze by Lysyl oxidase
a-1 antitrypsin
—Inhibits elastase that destroys elastin of alveolar walls of lungs.
—Protects for emphysema and COPD.
—Smoking inactivates it by oxidizing Met resided 351 and 358
