A.A.s, Protein Structure + Function

Question 1

Which macromolecules are dominant in terms of % body composition ?
How are women diff. To men?

Answer 1

proteins+lipids dominant
Men have same amount of protein and fat. They have more protein less fat than women

Question 2

Define amino acids - how much of body’s dry weight do they form

Answer 2

Monomers of proteins - 1/2 of body dry weight

Question 3

What are side chains? How many?

Answer 3

R groups - 20

Question 4

Does main chain change? Why’s it important ?

Answer 4

Invariant - imp. Properties of pH, optical isomers, peptide bond formation, reactivity

Question 5

Structure of alpha amino acid ?

Answer 5

YK

Question 6

2 termini? Residue no. 1 ? Whats always on left? So what’s on right?

Answer 6

C and N terminus
N-terminus is R1
NH3+
COO-

Question 7

What are oligopeptides

Answer 7

Small proteins of <40 AA’s

Question 8

What are oligopeptides

Answer 8

Small proteins of <40 AA’s

Question 9

Give an example of the following, incl. name and function.

Protein w 1,2,3,4 polypeptide chains:

Answer 9

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

Question 10

What do all hydrophilic side chains have that contributes to this characteristic? So where r they found?

Answer 10

Have =o, oh or no groups- form h-binds w water
So found in active sides

Question 11

What group/charge is associates w acidic side changes?
Some roles?

Answer 11

COO- (carboxyl group)
active sites and sale bridges

Question 12

What are the 3 basic sidechaines and what group?

Answer 12

Lysine, arginine, histidine
NH group

Question 13

Group in hydrophobic sidechaines ? Where are they found and why

Answer 13

Mainly C-H - little H2O interaction
Buried in core of water soluble proteins

Question 14

3 types of proteins?

Answer 14

Fibrous
Globular
Hybrid / fibrous-globular proteins

Question 15

4 examples of fibrous proteins, their location and function

Answer 15

-collagen, bones, tensile strength
-elastin, ligaments, elastic strength
-proteoglycans, bone, elastic strength
-keratin, hair/skin, external protection

Question 16

Globular protein functions (7)

Answer 16

Enzymes (2), transporters(2), protection, hormones, dna binding, storage, toxins, cell signalling

Question 17

Give name, location and function of some proteins

Answer 17

Trypsin - stomach - cleaves proteins
Lysozyme - tears - antibacterial
Haemoglobin - blood - o2 transport
Transferrin - blood, fe transport
Immunoglobulins - blood - immune response
Insulin - pancreas- glucose regulator

Question 18

2 types of hybrid proteins, 3 examples w location and function

Answer 18

Contractile - actin - muscle - thin filament
Myosin - muscle - thick filament

Protection - fibrinogen - blood - clotting

Question 19

Sources of protein diversity

Answer 19

-20 diff AAs w many combinations
-modifications such as metals, prosthetic groups, glycochains, phosphates, ect
-folding up into diff 3D structures

Question 20

4 diff levels of protein structure and definition

Answer 20

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

Question 21

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

Answer 21

Helical protein single main-chain - repeats every 4th residue .
R-groups outside , h-bonds between all c=o and n-h groups

Question 22

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

Answer 22

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)

Question 23

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?

Answer 23

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

Question 24

Define super secondary structures

3 major protein structure classes ?
Give example of each

Answer 24

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

Question 25

Compare fibrous and globular proteins in terms of: - structure -solubility -secondary structure -quaternary structure -functions in body and some locations

Answer 25

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)

Question 26

Give function of following fibrous proteins and structure : a-keratin, elastin and collagen

Answer 26

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

Question 27

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?

Answer 27

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

Question 28

Structure and function of fibrinogen?

Answer 28

- 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 )