Ion-exchange chromatography fundamentals: which matrix is positively charged (anion exchanger)? Select the resin that carries positive charges and binds anionic proteins or nucleic acids.

Introduction / Context:
Ion-exchange chromatography separates biomolecules based on charge interactions with a functionalized matrix. Correctly identifying resin charge is essential for method design and buffer selection.

Given Data / Assumptions:

• DEAE (diethylaminoethyl) groups are positively charged under typical pH, forming anion exchangers.
• CM (carboxymethyl) and phospho groups are negatively charged, forming cation exchangers.
• Target binding depends on analyte net charge at the working pH.

Concept / Approach:
A positively charged resin binds negatively charged analytes (anions). DEAE cellulose, a weak anion exchanger, is widely used for proteins and nucleic acids. In contrast, CM cellulose and phosphocellulose bind cations.

Step-by-Step Solution:
Classify functionalities: DEAE is basic (positively charged), CM and phospho are acidic (negatively charged).Map to exchanger type: DEAE → anion exchanger; CM/phospho → cation exchangers.Select DEAE cellulose as the positively charged matrix.

Verification / Alternative check:
Manufacturer datasheets list DEAE as anion-exchange media and CM/phospho as cation-exchange media, confirming the assignment.

Why Other Options Are Wrong:
CM cellulose and phosphocellulose carry negative charges; they are not positively charged matrices. “None of these” is incorrect because DEAE is correct.

Common Pitfalls:
Confusing exchanger type with the charge of the bound analyte; anion exchangers are positively charged resins that bind anions.

Final Answer:
DEAE cellulose.