SL - Carboxyl Flashcards
How are triglycerides converted to fatty acids and glycerol?
Using Lipases
How does carboxyl substitution occur under basic conditions? (2)
- The lone pair of the nucleophile attacks the carboxyl group, causing the double bond to break
- The lone pair of electrons on oxygen regenerate the double bond as the leaving group departs
* Addition-Elimination
What are the first 3 steps involved in carboxyl substitution under acidic conditions?
- Protonation of the C=O group on oxygen
- Nucleophilic attack by oxygen lone-pair from H2O (carboxyl breaks)
- Deprotonaton of -H2O group
What are the last 3 steps involved in carboxyl substitution under acidic conditions?
- Protonation of the X leaving group with oxygen lone pair
- Regeneration of the double bond and leaving group departs
- Deprotonation of OH to reform the carboxyl
Under what conditions are carboxylic acids converted? and why?
ACIDIC
- Under basic conditions, the carboxylic acid is deprotonated
What is Chymotrypsin?
A digestive enzyme- memebr of the serine protease family
Where does Chymotrypsin hydrolyse proteins?
In the small intestine
What 3 amino acids are involved in the catalytic triad of Chymotrypsin?
- Asp-102
- His-5
- Ser-195
What are the first 3 steps involved with the mechanism of serine proteases?
- Hydrogen bonding of His-57 and Asp-102 results in the activation of the OH group of Ser-195
- Once the substrate is introduced, a proton is transferred from Ser-195 to His-157
- Proton remains on histidine
What are the final 3 steps involved with the mechanism of serine proteases ?
- Acylation occurs, leaving an acyl-enzyme intermediate
- The acyl intermediate is hydrolysed with water (deacylation)
- The catalytic triad is reformed and another peptide is hydrolysed
How is charge stabilised within the serine protease mechanism?
By an oxyanion hole
How is amide hydrolysis important in the HIV life cycle
Chops up long (HIV) polypeptides into functional proteins
