A.A.s, Protein Structure + Function Flashcards
Which macromolecules are dominant in terms of % body composition ?
How are women diff. To men?
proteins+lipids dominant
Men have same amount of protein and fat. They have more protein less fat than women
Define amino acids - how much of body’s dry weight do they form
Monomers of proteins - 1/2 of body dry weight
What are side chains? How many?
R groups - 20
Does main chain change? Why’s it important ?
Invariant - imp. Properties of pH, optical isomers, peptide bond formation, reactivity
Structure of alpha amino acid ?
YK
2 termini? Residue no. 1 ? Whats always on left? So what’s on right?
C and N terminus
N-terminus is R1
NH3+
COO-
What are oligopeptides
Small proteins of <40 AA’s
What are oligopeptides
Small proteins of <40 AA’s
Give an example of the following, incl. name and function.
Protein w 1,2,3,4 polypeptide chains:
1) myoglobin - O2 transport in muscles
2) insulin a and b chain
3) colleges triple helix - tendons and bones
4) haemoglobin 2 a and b chains
What do all hydrophilic side chains have that contributes to this characteristic? So where r they found?
Have =o, oh or no groups- form h-binds w water
So found in active sides
What group/charge is associates w acidic side changes?
Some roles?
COO- (carboxyl group)
active sites and sale bridges
What are the 3 basic sidechaines and what group?
Lysine, arginine, histidine
NH group
Group in hydrophobic sidechaines ? Where are they found and why
Mainly C-H - little H2O interaction
Buried in core of water soluble proteins
3 types of proteins?
Fibrous
Globular
Hybrid / fibrous-globular proteins
4 examples of fibrous proteins, their location and function
-collagen, bones, tensile strength
-elastin, ligaments, elastic strength
-proteoglycans, bone, elastic strength
-keratin, hair/skin, external protection
Globular protein functions (7)
Enzymes (2), transporters(2), protection, hormones, dna binding, storage, toxins, cell signalling
Give name, location and function of some proteins
Trypsin - stomach - cleaves proteins
Lysozyme - tears - antibacterial
Haemoglobin - blood - o2 transport
Transferrin - blood, fe transport
Immunoglobulins - blood - immune response
Insulin - pancreas- glucose regulator
2 types of hybrid proteins, 3 examples w location and function
Contractile - actin - muscle - thin filament
Myosin - muscle - thick filament
Protection - fibrinogen - blood - clotting
Sources of protein diversity
-20 diff AAs w many combinations
-modifications such as metals, prosthetic groups, glycochains, phosphates, ect
-folding up into diff 3D structures
4 diff levels of protein structure and definition
Primary - sequence of AA , ect like glycosylations and prosthetic groups
Secondary - 3D structure of mainchain - a helix or b pleated sheet , h bonds only
Tertiary - 3D structure of main and side chain - hydrophilic/hydrophobic bonds, disulphide bridges, ionic, covalent hydrogen bonds
Quaternary - interaction of subunits/ polypeptide chains
Describe the alpha helix structure.
How often does it repeat itself? R-group positions? What type of bonds, and they form between what ?
Draw it on one note
Helical protein single main-chain - repeats every 4th residue .
R-groups outside , h-bonds between all c=o and n-h groups
Beta pleated sheet structure ?
How do h-bonds form?
R-group positions?
Sheets are what to each other? 2 types?
Draw one on one-note
Multiple main chains
H-bonds form between separate main chains - perpendicular to flow
Alternate up and down
Sheets can be parallel (w n termini at same end) or perpendicular (w n termini at opp ends)
What are b-turns and loops, where are they found, why, how do they interact w water?
What’s often located mid b-turn and why
How r they diff to beta pleated sheets?
Conformational extremes - at surface of globular proteins - link together a-helices and b-strands in core - hydrophilic
B-turns steric ally demanding , so Gly residue in middle
-involve sharp reversal in direction of protein chain over 4 residues
Define super secondary structures
3 major protein structure classes ?
Give example of each
All secondary structures inside structure
All a-helix , e.g. globin
All B-pleated sheet , e.g. immunoglobulin fold of antibodies
Mixed , e.g. TIM fold
Compare fibrous and globular proteins in terms of:
- structure
-solubility
-secondary structure
-quaternary structure
-functions in body and some locations
G:
-compact
-soluble in water
-complex w mix of 3 types of structures (alpha helix ect)
-held together w non-covalent forces
-metabolism functions (e.g. Enzymes, immunity, hormones)
F:extended
- insoluble in water
-simple - based on 1 type
- held together by covalent bridges
-structure of body (e.g. bone, skin, hair)
Give function of following fibrous proteins and structure : a-keratin, elastin and collagen
1) external protection + toughness (e.g. hair and nails) - 2 long a-helices w disulphide bridges - bundle into fibres
2) connective tissue linked to elasticity and stretch ability(e.g. arteries and lung walls) - elastin fibres cross linked by covalent bonds
3) connective tissue linked to tensile strength (e.g.tendons and bones) - triple helix - tropocollagen subunits into fibre - chemical cross links
Give the structures of haemoglobin, globin and immunoglobulins (function and structure of each fragment and overall molecule)
Draw structures on one note
How does the body solve issue w haem groups being insoluble in water?
1) - 4 polypeptide chains (2 a 2 b chains) w 4 haem groups
2) 1 polypeptide chain w 1 haem
…. Haem group becomes soluble in water when bound to O2 (oxyhemoglobin)
3) B-sheet structure - Y shaped - 2 light 2 heavy chains
2 Fab fragments (recognise antigens - antigen binding site) and 1 Fc - effects immune response - receptor binding site
Structure and function of fibrinogen?
- mix of a helices and b sheets - has globular regions (enables self assembly for fibre network formation), and fibrous regions ( enable insoluble clot formation - wound sealed )
