Week 4: Protein Sequence Info Flashcards
What are 3 implications of common genetic code?
- Evidence of life’s unity 2, molecular evolution 3. recombinant protein expression and engineering.
Describe evolution of myoglobin.
Myoglobin - 153 residues - sequence comparable b/w mammals - few conservative and nonconservative subs.
What is an invariant residue?
Invariant residues - positions in aligned sequences where exact residue match
What is a conservative substitution
similar but not exact
What is identity?
percent of invariant residues b/w sequences
What is similarity?
percentage of conservative subs and invariant residues between aligned sequences.
How are invariant and variant subs displayed?
*= invariant, : = conserved sub
What do multiple sequence alignments show?
reveal evolutionary relationships.
What does it mean if two protein sequences are > 25% identical?
They will have similar structures
What does it mean if two protein sequences are < 25% identical
may still have similar structures as fold is more highly conserved than sequence.
What does sequence determine?
Fold !
Describe myoglobin
Oxygen storage
Describe hemoglobin
Oxygen transport
Describe Ascaris globin
protects parasitic intestinal worm from oxygen toxicity
Describe leghemoglobin
protects bacterial nitrogenase in root nodules of plants