Protein Structure and Function Flashcards
how many animo acids are there and what is the basic structure
- 20 amino acids
- carbon with:
- carboxyl group
- amino group
- side chain R
- hydrogen
how do amino acids join together and what is the name of the bond
- condensation reaction releasing H2O
- peptide bond
what is the name of the reaction that separates animo acids
hydrolysis
what is a conjugated protein
proteins that contain chemical components as well as amino acids
what is a prosthetic group
The non amino acid part of a conjugated protein
what are the 4 levels of protein structure
- primary - aa sequence
- secondary - a helix/ b sheets
- tertiary - 3D folding
- quaternary - more than one polypeptide chain joined together
what is the shape of a polypeptide chain and is it flexible
- planar
- no, it is rigid
Which level of protein structure does not involve hydrogen bonds?
primary
what level of protein structure determines if the protein is globular or fibrous
secondary
what is used to identify primary structure
mass spectrometry
why are a helix abundant in proteins located in the cell membrane
because the hydrophilic polypeptide backbone is
H-bonded to itself (no polar groups exposed) in the α helix and shielded from the hydrophobic lipid membrane.
why is hydrogen bonding stronger in antiparallel b sheets
because the C=O and N-H groups are better aligned
why are b turns common in globular proteins
this structure allow some
amino acid residues to form turns and loops and assume a very compact structure
how to identify secondary structures
circular dichroism spectroscopy
Any form of structural asymmetry in a molecule
gives rise to differences in absorption of polarized
light.
what forces create tertiary structure
disulfite bonds, salt bridges and hydrogen bonds.
what is the basic structure of fibrous and globular proteins
- fibrous: long strands or sheets
- globular: spherical or globular shape
are fibrous proteins soluble or insoluble in water
insoluble
are globular proteins soluble or insoluble in water
soluble
hydrophobic residues are hidden inside whereas hydrophilic stick outside
3 examples of fibrous proteins
- alpha keratin
- collagen
- silk fibroin
3 examples of globular proteins
- myoglobin
- lysozyme
- antibodies
how many molecules of O2, CO2, H+, and BPG (2,3-bisphosphoglycerate) can Hemoglobin carry
- 4 molecules of O2 or 4 molecules of CO2
- H+ can bind to any of the several aa’s
- only 1 molecule of BPG can bind
A single molecule of Hb can bind the fewest of which ligand?
BPG
What is the benefit of increasing [BPG] in
erythrocytes at high altitude?
hemoglobin will have a lower affinity for O2 and will be able to release more O2 to the tissues and cells of our body
Which of the following best describes haem?
* Metalloprotein
* Prosthetic group
* Conjugated protein
* Motif
prosthetic group
