. The pI is called ________________. The rule of calculating pI of an amino acid is that first, write the dissociation equation
from fully protonated form to fully deprotonated form, label the charge of each form; second, identify the zwitterionic form (zero charge) and find the closest pKs (left and right side in the dissociation equation); third, average these two pKs. Write the dissociation equations for amino acids, glutamate, histidine, and calculate their pIs.
1 answer:
Answer:
The isoelectric point is that the <u>pH </u>at which the compound is in an electronically neutral form.
For diss equations<u>, p</u>lease find them in the enclosed file.
The pIs of 2 amino acids:
- Glutamate: pI = 3,2
- Histidine: pI = 7,6
Explanation:
Formula for the pI calculation: pI = (pKa1 + pKa2)/2
Given 3 pKa :
- Acid glutamic with an acid sidechain:
Use the lower 2 pKas (corresponding with 2 -COOH groups)
pKa1 = 2,19; pKa2 = 4,25; so pI = 3,2
- Histidine with 2 amino groups:
Use the higher 2 pKas ( -COOH group and -NH= group)
pKa1 = 6; pKa2 = 9,17; so pI = 7,6
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Answer:
The solution to the given problem is done below.
Explanation:
a)
i) =( 0.002 μg / L )( 1mg / 1000 μg )( 1L / kg )( 1000 mil / 1 billion) = 0.002 ppb
ii) =( 0.002 μg / L )( 1mg / 1000 μg )( 1L / kg )( 1,000,000 mil / 1 trillion) = 2 ppt
iii) =( 0.002 μg / L )( 1 mole / 540g ) = 3.7 x μM.
b)
i) =( 0.002 μg / g ) = 0.002 ppm
ii) In solids, ppb = μg/kg
=( 0.002 μg / g )( 1000 mil/ 1 billion) = 2 ppb