Question

Q.3)
Iso electric point of type B gelatin is at (1 marks )
Ans.
PH 9
PH 2.6
pH3.2
pH 4.7​

Answer 1

Answer:

Answer is at pH 4.7

...........

Answer 2

I have learned that the isoelectric point (pI) of a substance (typically an amino acid or a protein) is calculated as its average pKa, so I suppose that a substance of lower pI would have lower average pKa and be more acidic/less alkaline. However I came across some information about gelatin type A and type B in Handbook of Pharmaceutical Excipients (6th Edition) as following:

"Acidity/alkalinity: For a 1% w/v aqueous solution at 25oC (depending on source and grade): pH = 3.8–5.5 (type A); pH = 5.0–7.5 (type B)

Isoelectric point: 7.0–9.0 for type A; 4.7–5.4 for type B"

4.8 to 5.1

4.8 to 5.1It has been reported that gelatin type A possesses an isoelectric point (IP) of 7–9, while gelatin type B is characterized by an IP ranging from 4.8 to 5.1