Protein Structure

Question 1

Proteins are

Answer 1

polymers of amino acid monomers

Question 2

Structure of amino acids

Answer 2

Have the same basic structure, Carboxyl group and amine group differing only in R group present.

R group varies in size, shape, charge, hydrogen bonding capacity and chemical reactivity

Question 3

Types of R groups

Answer 3

Basic(+)
Acidic(-)
Polar
Hydrophobic

Question 4

Negatively charged acidic amino acids have

Answer 4

a COOH grouyp and are HYDROPHILIC

Question 5

Positively basic charged amino acids are

Answer 5

Hydrophilic and have an AMINE group NH

Question 6

Polar amino acids have

Answer 6

Hydrophilic groups like C=O OH NH

Question 7

Hydrophobic amino acids hve

Answer 7

Hydrocarbon group

Question 8

Primary structure

Answer 8

Sequence of amino acids

Question 9

Secondary structure

Answer 9

Beta pleated sheets and alpha helices, resulting from hydrogen bonding along backbone

Question 10

Tertiary

Answer 10

Polypeptide folded to form a more complex 3 Dimensional structure held together by interactions between R groups

Question 11

Interactions between R groups

Answer 11

Hydrophobic interactions
LDF
Hydrogen Bonding
Ionic Salt bridge
Disulfide Bonds

Question 12

Hydrophobic interactions

Answer 12

Hydrophobic R groups are mostly arranged to the inside of a protein

Question 13

Ionic salt bridge

Answer 13

COOH and NH2 ionise to become COO- and NH3+ which strongly attract each other

Question 14

Disulphide Bondss

Answer 14

covalent bonds between R groups containing sulphur

Question 15

Quaternary

Answer 15

**Exists in proteins with two or more connected polypeptide subunits,

Question 16

A prosthetic group

Answer 16

Non protein unit tightly bound to a protein and necessary for its function.

Question 17

Example of a prosthetic group

Answer 17

The ability of haemoglobin to bind oxygen is dependent on the non protein haem group

Question 18

What can the interactions of the R groups be influenced by

Answer 18

Temp and pH.

Question 19

Temp on Protein stryucrure

Answer 19

Increasing temp disrupts interactions and the protein begins to unfold becoming denatured

Question 20

pH on protein strucrure

Answer 20

Charges on acidic and basic R groups are affected by pH

as it increases from optimum, normal ionic interactions between charged groups are lost=gradually changing conformation of protein until its denatured

Question 21

Ligand

Answer 21

Substance that can bind to a protein

Question 22

Ligand binding

Answer 22

R groups not involved in protein can allow ligands to bind, Binding sites will have complementary shape and chemistry to ligand

Conformation of protein changes on bonding allowing functional change

in the protein

Question 23

Allosteric interactions

Answer 23

. Binding of a substrate to active site of an allosteric enzyme increases affinity of other active sites for binding of subsequent substrate molecules.

can occur between spatially distinct sites

Question 24

Allosteric enzymes

Answer 24

• Contain allosteric site
• Many Consist of multiple subunits(quaternary)

Question 25

Modulators

Answer 25

Regulate activity of enzymes when they bind to the allosteric site

Question 26

After modulator binds

Answer 26

Conformation of enzyme changes and this alters the affinity of the active site for substrate. Positive ones increase affinity, negativity decreases it.

Question 27

Allosteric enzymes with multiple sub units show

Answer 27

Cooperativity in binding! so changes in binding at one sub unit alter affinity for remaining ones

Question 28

Example of cooperativity

Answer 28

Binding and release of Oxygen in Haemoglobin Changes in binding of oxygen at one SU alter affinity of remaining SUs of oxygen

Question 29

Influence and physiological importance of temp & pH on binding of oxygen

Answer 29

A decrease in pH/increase in temp lowers affinity of haemoglobin for 02, so binding of 02 is reduced.

Question 30

Decreased binding of oxygen to haemoglobin promotes

Answer 30

Increased oxygen delivery to tissue in actively respiring tissue.

Question 31

# What Do protein kinases' and protein phosphatases catalyse?

Answer 31

Kinases catalyse transfer of a phosphate group to other proteins | Phosphatases catalyse reverse reaction ## Footnote Terminal phosphate of ATP is transferred to specific R groups

Question 32

Phosphprylation brings about

Answer 32

Conformational changes which affect a proteins actvivity | proteins are activated/inhibited ## Footnote The activity of many cellular proteins(enzymes receptors) is regulated this way