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Flashcards in Protein Structure Deck (27)
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1

Definition of primary

Sequence of AA in peptide chain

2

Definition of secondary

Folding of chain into a helix/b pleated sheets

3

Definition of tertiary

Peptide chain folds upon itself

4

Definition of quaternary

Folded peptide chains joined together

5

Functional groups on amino acids

Amino
Carboxyl

6

Reactions between amino acids and dipeptides

Dehydration/synthesis
Acid hydrolysis

7

Properties of peptide bonds

Has characteristics of C=C
However, C-N bond length shorter than expected, no rotation, trans groups
Partial -ve on O
Partial +ve on N
HB can form between 2 polar AA

8

Direction of polypetides

NH3+ = N terminal
COO- = C terminal

9

Covalent linkages, post translation modification

Disulphide bridges Cys-Cys
Glycosylation
Phosphorylation
Methylation via NH2 groups

10

How does glycosylation work

Sugars bind to OH of Thr, Her
Sugars bind tp NH2 of Asn

11

How does phosphorylation affect proteins

Cell signal transduction
Change in enzyme activity

12

How does methylation via NH2 groups affect proteins

Histones and gene expression

13

Properties of a helices

HB in same PP chain, not between side chains
HB formed between COOH, NH2 of every 4th peptide
RH helix
Turn stabilized by HB
R groups on outside
Rigid cylinder, support for protein

14

Properties of b pleated sheets

Linear peptide chains
HB between chains holds strands in B sheet
Side chains in each strand alternately lie above and below sheet plane

15

Properties of collagen triple helix

3 chains with HB between chains
LH helix
Gly, Pro, hydroxypro, repeated sections

16

Forces that stabilize protein structure

Covalent (disulphide bridges)
HB
IB
LF
Hydrophobic effects

17

How do HB work

2 delta -ve atoms compete for the same H atom
Between H and lone electron pair on O, N

18

How do IB work

Between charged side chains
Asp, Glu COO-
Arg, Lys NH3+

19

How do LF work

Sum of attractive/repulsive forces between molecules
Unequal distribution of electrons results in instantaneous dipoles

20

How do hydrophobic effects work

Fold in a way to minimize contact with water
Cannot form HB due to hydrophobic R groups

21

How to disrupt protein structure and function

pH
Temperature
Ionic strength

22

How are proteins folded

All proteins have different structures but only 1 is functional
Primary structure encodes pathway that leads to final structure which is most stable

23

What can misfiled proteins result in

Mutations can cause a protein to fold incorrectly
If not folded properly, stable protein aggregates can form

24

Neurological symptoms in Creutzfeldt Jakob disease

Walking difficulties
Slurred speech
Numbness
Dizziness
Visual problems

25

Psychological symptoms of Creutzfeldt Jakob disease

Severe depression
Withdrawal
Anxiety
Irritability
Insomnia

26

What happens to the normal prion proteins

Normal cellular prion proteins become pathogenic prion proteins

Pathogenic prions can form fibril aggregates

27

Compare the structures of prion proteins

PrPc
a helix, no b sheets
Susceptible to proteolysis

PrPsc
less a helix, b sheet present
Protease resistant

Both have the same AA sequence