protein instabilities; protein formualtions

Question 1

what is a protein stabilised by

Answer 1

Non-covalent
interactions
• Ionic interactions
• Salt bridges
• Van der Waals
interactions
• Polar interactions
(hydrogen bonds) 

AND

2. Disulfide bridges
   (between two cysteine
   residues)

Question 2

what can changes in non-covalent interactions result in

Answer 2

aggregation
protein
misfolding or unfolding

Question 3

Any changes in the protein environment may trigger

Answer 3

r degradation, aggregation

and/or inactivation.

Question 4

name the 5 formulation challenges

Answer 4

• storage stability
• container and closure systems
• conformational stability during different steps of manufacturing and formulation process
• high viscosity of formulations due to requirement for high doses
• prevent all possible chemical and physical degradation pathways

Question 5

physical protein instabilities

Answer 5

aggregation

Question 6

chemical protein instabiltities

Answer 6

cross link
oxidation
hydrolysis
mail lard reaction

Question 7

factors affecting protein stability

Answer 7

Temperature
• pH
• Ionic strength (salts and non-aqueous solvents)
• Metal ions and chelating agents
• Protein concentration
• Surface

Question 8

how does temp affect proteins

Answer 8

As you increase temp, you change the energetics of system, protein unfolds, more energy in, protein melts and unfolds

Question 9

how does ph affect proteins

Answer 9

At isoelectric point; pH is 0 and they will be affected.

Question 10

which proteins are more prone to degdration

Answer 10

• Denatured/unfolded proteins

Question 11

which reaction is the the most common degradation reaction

Answer 11

deamidation

Question 12

which proteins are most prone to deamidation

Answer 12

glut and asparagine

Question 13

what does deamidation depend on

Answer 13

ph

Question 14

whihc side chains are prone to oxidation

Answer 14

his met cys trp and tyr

Question 15

where do oxidation reactions take place

Answer 15

presence of
transition metal ions or
upon exposure to light

Question 16

which bonds are prone to hydrolysis

Answer 16

Bonds between

Asp-Gly and AspPro

Question 17

which amino acids are prone to racemic conversion

Answer 17

all amino acids apart from gly

Question 18

what is rate of isomerisation influenced by

Answer 18

location and the
mobility of the amino
acid side chain

Question 19

Aspartic acid and
asparagine can form
isoaspartic acid via which intermediate

Answer 19

succinimide

intermediate