Molecular structure of proteins Flashcards
Describe how proteins are molecularly visualised
Converts atomic coordinate data in computer codes => recreate 3D model
List the types of ways the structure of protein is visualised
Stick, Ball & stick, Space-filled, cartoon & ribbon, opaque, plastic, metal
List the roles of proteins (9)
- Catalysis: enzyme
- Transport: haemoglobin
- Storage
- Motion: Myosin
- Structural support: collagen
- Immunity: antibodies
- growth: (growth) hormone
- Communication: hormones
- Regulation: of genes (epigenetics)
Hierarchy of protein structure
1º: sequence of AA
2º: a-helix, B-sheet, B-turn, loop
supersecondary: looks at 2º that are adjacent to each other (a-a / B-a-B /B-B)
domains: looks @ structural/functional units in protein (note: same domains can be found in diff. proteins)
3º: native structure/conformation = final 3D shape
4º: 2+ proteins covalently bound to each other
What are prosthetic groups & e.g.?
metal/organic molecules COVALENTly bond to protein & essential for protein to function (cofactor) e.g. heme
Forces that affect protein folding
2º structure: H-bond
3º: interaction b/w side chains & H2O
- hydrophobic force (=> hydrophobic core in globular protein)
- H bonds
- Ionic
- Disulphide bonds
What happens to misfolded proteins & e.g. if possible?
- Tagged & degraded by cell OR
- lead to disease like:
- amyloidosis (Alzheimer’s disease)
- prion disease
Characteristics of proteins (9: 7 new, 2 known)
- Highly specific & act through 3D stereospecific interactions
- Classified into families: same AA sequ. w/ same 3D structure (domain)
- Described as globular or fibrous proteins
- Structures are dynamic: can change shape to respond to stimulus or do its function
- form specific protein-protein interactions
- Some require prosthetic groups or cofactors to function
- ionisable side chains can act as buffers
- aka polypeptides = chain of AA bond w/ peptide bond
- directionality N to C terminus
