An amino acid is characterized by two `pKa` values the one corresponding to the more acidic site is designated as `pKa_(1)` and the other corresponding to the less site is designated as `pKa_(2)`. Some amino acids have side chain with acidic or basic groups. These amino acids have `pKa_(3)` value also for the side chain.
`|{:(S.No,"Amino acid",P^(Ka1),P^(Ka2),P^(Ka3)" (Side chain)"),(I,"Aspartic acid",1.88,9.6,3.65),(II,"Glutamic acid",2.19,9.67,4.25),(III,"Lysine",2.18,8.95,10.53),(IV,"Arginine",2.17,9.04,12.48):}|`
The isoelectric point `(pI)` of Aspartic acid and lysine will be respectively `:`

Options

A. The superoxide ion `(i.e. O_(2)^(-))` is stable only in presence of larger cations such as `K^(+),Rb^(+),Cs^(+)`
B. Alkali metals are normally kept in kerosene oil.
C. All the alkali metal hydrides are ionic solids with high melting points.
D. The concentrated solution of alkali metals in liquid ammonia is paramagnetic in nature.

Explanation

To calculate the isoelectric point (pI) of aspartic acid and lysine, we will follow these steps:

### Step 1: Understand the concept of isoelectric point (pI)
The isoelectric point (pI) is the pH at which an amino acid has no net charge. For amino acids with acidic side chains, the pI is calculated using the pKa values of the acidic group (pKa1) and the side chain (pKa3).

### Step 2: Identify the pKa values for aspartic acid
From the given data:
- pKa1 (more acidic site) = 1.88
- pKa3 (side chain) = 3.65

### Step 3: Calculate the pI for aspartic acid
For aspartic acid, the formula to calculate the pI is:
\[ pI = \frac{pKa1 + pKa3}{2} \]
Substituting the values:
\[ pI = \frac{1.88 + 3.65}{2} = \frac{5.53}{2} = 2.765 \]

### Step 4: Identify the pKa values for lysine
From the given data:
- pKa1 (more acidic site) = 2.18
- pKa2 (less acidic site) = 8.95
- pKa3 (side chain) = 10.53

### Step 5: Calculate the pI for lysine
For lysine, the pI is calculated using the pKa values of the less acidic group (pKa2) and the side chain (pKa3):
\[ pI = \frac{pKa2 + pKa3}{2} \]
Substituting the values:
\[ pI = \frac{8.95 + 10.53}{2} = \frac{19.48}{2} = 9.74 \]

### Final Answer
The isoelectric point (pI) of aspartic acid is 2.765, and for lysine, it is 9.74.

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