Imines, acids and bases Flashcards
What is the green fluorescent protein isolated from?
The pacific JellyfishL Aequoria Victoria
Tell me about the structure of the GFP?
- 238 amino acids
- Beta sheets are present (green)
- Alpha helices are present (blue)
- There are connecting loops between the alpha and beta sheets (yellow)
Whats the general structure of an imine?
Write the reactions for the formation of Imines when an aldehyde/ Ketone react with a promary amine ?
Whats necessary to drive the reaction of the formation of an amine in a lab?
the removal of water
What type of reaction is the the reverse of imine formation?
Dehydration
Comeplete the following reaction;
Draw the overall mechanism of imine formation
The mechanism for the formation of imine is split into 2 parts, write out the first part (hemiacetal formation)
include; structures, intermediates
Compare hemiaminal formation with hemiacetal formation
Write the reaction for the second part of imine formation (onto the imine)
include; structures, intermediates
Draw the reaction for an aldehyde/ ketone reacting with a secondary amine.
What is the name of the product formed as well
Draw the reaction mechanism for when an aldehyde/ketone reacts with a secondary amine
What is this structure?
What can imines be formed from?
from pyridoxal phosphate as the aldehyde component
Tell me the steps to how the release of Ca2+ from Aequoria leads to it fluorescing
- The calcium ions bind to a protein called aequorin which releases blue light upon calcium binding. The blue light is absorbed by green fluorescent protein which in turn gives off green light.
- The part of a molecular structure which absorbs light and re-emits at longer wavelength is called the fluorophore.
- The GFP fluorophore is derived from a group of three amino acids found in the center of the barrel: Ser65, Tyr66, Gly67
- The reaction which causes this triplet of amino acids to fluoresce is very closely related to imine/enamine formation.
Draw the structure of the 3 amino acids joined together at the centre of the barrell of the GFP?
How have a number of fluorescent proteins now been developed?
using protein mutagenesis
How can the emission wavelength (colour) be tailored?
by changing the amino acid residues located near the tripeptide fluorophore
How is the strength of a Brønsted acid defined?
include a reaction
By how well it transfers H+ to H2O
Whats the eqaution for the equilibrium constant?
Whats the strong acids dissociation formula?
What has a smaller PKa, strong or weak acids ?
stronger acids
A table to show substances, their structure, PKa values
Whats a Brønsted base and write an equation to show this?
A Brønsted base is a species which accepts H+ in a reaction
What is the strength of a Brønsted base related to?
Write an equation to support this?
The strength of a Brønsted base is related to the strength of its conjugate acid i.e. consider the acid dissoctiation equilibrium for BH+
If BH+ is a weak acid (its PKa is high) this equilibrium lies to which direction?
What does this correspond to?
Write the acid dissociation formula for Brønsted bases?
In a reaction between a Brønsted acid and base, what can we calculate and how?
We can calculate the position of the equilibrium by comparing the PKa vlaues of the two acids involved
