To determine the Isoelectric point of a Protein, Isoelectric focusing

To determine the isoelectric point of a protein, first establish that a gel:

(a) Contains a denaturing detergent that can distribute uniform negative charges over the protein’s surface.
(b) Exhibits a stable pH gradient when ampholytes become distributed in an electric field.
(c) Is washed with an antibody specific to the protein of interest.
(d) Neutralizes all ionic groups on a protein by titrating them with strong bases.

The correct answer is:

(b) Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

Explanation:

To determine the isoelectric point (pI) of a protein, isoelectric focusing (IEF) is used. IEF relies on a stable pH gradient created by ampholytes (small charged molecules) in an electric field.

  • Proteins migrate within the gradient until they reach their isoelectric point (pI), where their net charge becomes zero and movement stops.
  • (a) Incorrect: SDS is used in SDS-PAGE, not IEF. It denatures proteins and applies a uniform negative charge, making pI determination impossible.
  • (c) Incorrect: Washing with antibodies is a step in Western blotting, not isoelectric focusing.
  • (d) Incorrect: Titrating ionic groups with strong bases does not determine pI; instead, proteins naturally stop moving at their pI in a stable pH gradient.

 

 

46 Comments
  • Arushi
    March 3, 2025

    👍👍

    • Monika jangid
      August 14, 2025

      Amphotlyte separate protein on the basis of iso electric point or charge

  • Prami Masih
    March 4, 2025

    Done ✅ sir

  • Anjani sharma
    August 14, 2025

    Answer b is correct as in isoelectric focusing point the proteins migrate with ph gradient until net charge is zero

  • Karishma Don
    August 14, 2025

    It is achieved using ampholytes, which establish a stable pH gradient when an electric field is applied.

  • Mitali
    August 14, 2025

    (b) Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Soniya Shekhawat
    August 14, 2025

    Ist occuring IEF in which protein are separate on the basis of PH with the net charge of protein is be have zero so B is correct option .

    • Khushi Mehra
      August 14, 2025

      Iso electric point refers to the migration of protein within the gradient until the net charge on protein becomes zero . This can be done by adding ampholytes which can act as an acid as well as base.

  • Soniya Shekhawat
    August 14, 2025

    IEF in which protein are separate on the based of PH (ampholytes )with the net charge of protein is be have zero so B is correct option .

  • Khushi Mehra
    August 14, 2025

    Iso electric point refers to the migration of protein within the gradient until the net charge on protein becomes zero . This can be done by adding ampholytes which can act as an acid as well as base.
    Correct option is b

  • Urmi sisodiya
    August 14, 2025

    Option b is correct bcoz net charge of proteins have to be zero

  • Deepika sheoran
    August 14, 2025

    Option b is correct
    Because isoelectric focusing proteins move through a ph gradient until they reach a point where their net charge is zero.

  • Roopal Sharma
    August 14, 2025

    B is correct as protein is separated on the basis of oh gradient

  • Surbhi Rajawat
    August 14, 2025

    To determine isoelectric point we must have a Ph gradient which will help in neutralizing the protein therefore B is correct option

  • Ruchika
    August 14, 2025

    Option b is correct 👍

  • Ruchika
    August 14, 2025

    b is correct 👍

  • Shivani
    August 14, 2025

    Option b is correct .

  • Priya khandal
    August 14, 2025

    Exhibits a stable pH gradient when ampnolytesbecome distrbuted in a electric field

  • Ankita Pareek
    August 15, 2025

    To determine isoelectric point isoelectric focusing is used where proteins separate on the basis of their.. charge on proteins depends on ph ief is relies on stable ph gradient so option b is correct

  • Kajal
    August 15, 2025

    Exhibit a stable ph gradient when ampholyte gets distributed acc. To the PH gradient

  • Kavita choudhary
    August 15, 2025

    Answer is b

  • Divya rani
    August 16, 2025

    B is right answer because IEF is on stable pH gradient and in electric field so charge is important

  • Neeraj Sharma
    August 17, 2025

    Option b as we need a stable ph gradient to find the isoelectric point

  • Seema
    August 18, 2025

    👍

  • Shrddha
    August 23, 2025

    Amphobialite is a word that can donate and accept iones pi is the ph at which molecule has no net electric charge

  • Bharti Yadav
    August 24, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • MOHIT AKHAND
    August 24, 2025

    Done sir ✅

  • Priyanka Choudhary
    August 24, 2025

    B is correct answer,Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Anil Choudhary
    August 24, 2025

    Option b is correct because net charge of proteins have to be 0

  • Bhavana kankhedia
    August 24, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Alec
    August 24, 2025

    ans is b – establish a stable ph gradient when ampholytes are distributed in the electric field.

  • Anju
    August 24, 2025

    Ans:B
    In Isoelectric focusing protein moves with ph gradient till the net charge is zero

  • Anjali
    August 24, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Shivani Panwar
    August 24, 2025

    Answer B…👍

  • Devika
    August 24, 2025

    B is correct

  • Kashish yadav
    August 25, 2025

    👍👍

  • Ayush Dubey
    August 25, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • sakshi khatri
    August 25, 2025

    done

  • Shriyanshi verma
    August 30, 2025

    Option b is correct bcoz net charge of proteins have to be zero

  • Swati Choudhary
    August 31, 2025

    (b) Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Shobha Kanwar
    August 31, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Anisha jakhar
    September 3, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Muskan Yadav
    September 3, 2025

    Exhibits a stable pH gradient when ampholytes become distributed in an electric field.

  • Somya Yadav
    September 5, 2025

    Option b is correct
    Because isoelectric focusing proteins move through a ph gradient until they reach a point where their net charge is zero.

  • Aakansha sharma Sharma
    October 1, 2025

    Option b is correct
    Because isoelectric focusing proteins move through a ph gradient until they reach a point where their net charge is zero.

  • Harish Kumar
    November 18, 2025

    B Option is correct

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