Biochemistry - Structure and Properties of Amino Acids - Discussion
Discussion Forum : Structure and Properties of Amino Acids - Section 1 (Q.No. 11)
11.
Which of the following pairs of amino acids would carry a negative charge on their side chain at pH 8.0?
Discussion:
9 comments Page 1 of 1.
Nyalema said:
2 years ago
Well explained, Thanks all.
Syrous Arinaitwe said:
3 years ago
You did it, well explained.
Syrous Arinaitwe said:
3 years ago
You did it, well explained.
Abel said:
4 years ago
The question is every amino acid when placed in basic solution.
It will Cary a net negative charge.(Lippincott biochemistry) Nh3+----c-----coo- in basic solution Nh3+ will loss a proton and coo- remains.
It will Cary a net negative charge.(Lippincott biochemistry) Nh3+----c-----coo- in basic solution Nh3+ will loss a proton and coo- remains.
Nikhil said:
6 years ago
At alkaline, pH amino acids are in the form of cations so, at pH 8. 0 the amino loses its hydrogen group and forms an - ve charge.
Nikki said:
8 years ago
Consider these groups COOH, NH3, COOH.
At pH 8.0, the first COOH group loses its H+ because its pKa is BELOW 8.0.
At pH 8.0, the NH3 still has its proton because its pKa is ABOVE 8.0.
So we are so far left with a 0 charge.
But in Aspartate and Glutamate, we have an EXTRA COOH (R group), which has lost its proton at pH 8.0 because its pKa is BELOW 8.0.
So overall we have a -1 charge.
At pH 8.0, the first COOH group loses its H+ because its pKa is BELOW 8.0.
At pH 8.0, the NH3 still has its proton because its pKa is ABOVE 8.0.
So we are so far left with a 0 charge.
But in Aspartate and Glutamate, we have an EXTRA COOH (R group), which has lost its proton at pH 8.0 because its pKa is BELOW 8.0.
So overall we have a -1 charge.
(1)
Alby said:
8 years ago
pKr of Glutamate is 4.25.
pKr of Aspartate is 3.65.
If pH, for example the pH of 8, is greater than the pKr, then the amino acid loses a proton and bears its negative charge.
If the pH is less than the pKr value, then the amino acids keeps its proton, bearing a neutral charge.
PH of 8 is greater than the pKr values of Glu and Asp, so they both lose a proton and bear that negative charge on their respective are group.
pKr of Aspartate is 3.65.
If pH, for example the pH of 8, is greater than the pKr, then the amino acid loses a proton and bears its negative charge.
If the pH is less than the pKr value, then the amino acids keeps its proton, bearing a neutral charge.
PH of 8 is greater than the pKr values of Glu and Asp, so they both lose a proton and bear that negative charge on their respective are group.
Subarna said:
9 years ago
Why aspartate and glutamate carry -ve charge at ph 8?
Jyoti shah said:
9 years ago
Do not get the reason behind it?
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