Lecture 4 & 5 Flashcards
(27 cards)
Who won the Nobel Prize in 1958 for sequencing insulin?
Frederick Sanger
He proved that proteins had a defined ‘primary’ structure.
What technique did Frederick Sanger use for protein sequencing?
Edman’s Protein Sequencing
Developed by Pehr Edman in 1950.
What protease cleaves after R/K residues?
Trypsin
What protease cleaves after bulky hydrophobic amino acids?
Chymotrypsin
What is the pH used in the described protein sequencing process?
9.0
What is produced when cyanogen bromide (CNBr) cleaves a polypeptide?
Peptidyl homoserine lactone
How does mass spectrometry analyze proteins?
By digesting protein (trypsin), adding charge, and measuring time of flight to record mass spectrum
What is the primary structure of proteins?
The amino acid sequence
What is the average molecular weight of an amino acid?
110 Daltons
What is the molecular weight range of most proteins?
5.5-220 kD
What bonds cross-link between cysteine residues in proteins?
Disulfide bonds
What is the estimated molecular weight of a protein based on the number of amino acids?
Number of amino acids multiplied by 110
What is the role of the ribosome in cells?
It is the cell’s protein factory
True or False: Proteins are made by amino acid condensation.
True
Fill in the blank: DNA makes RNA makes _______.
Proteins
What is the significance of the amino acid sequence in molecular biology?
It allows for the production of specific proteins using a DNA sequence
What happens if we mix 2 amino acids in solution?
We do not get a dipeptide.
What is the cell’s protein factory?
The ribosome.
How do proteins evolve over time?
Proteins evolve from a common ancestor, and phylogenetic trees based on protein homology are consistent with those based on ribosomal RNA sequences or morphology.
What is the relationship between homologous proteins?
Homologous proteins have a common ancestral protein.
What is more conserved in proteins, structure or sequence?
Structure is more conserved than sequence.
What is involved in insulin maturation?
Insulin maturation involves the formation of three disulfide bonds and three proteolytic cleavages of the peptide bond, resulting in two disulfide-linked polypeptides.
What must be maintained in protein folding?
The stereochemistry of each amino acid must be maintained, including atomic connectivity, bond lengths, bond angles, and ring planarity.
What does the peptide plane restrict?
The peptide plane restricts torsion angles.
