Unit 1

• Cation Exchangers in Chromatography:
• Cation-exchange resins possess negatively charged functional groups that attract and bind positively charged molecules (cations):
• Carboxy-Cellulose and (D) Carboxymethyl-Cellulose (CM-cellulose): Weak cation exchangers bearing carboxylate groups ($-\text{O}-\text{CH}_2-\text{COO}^-$).
• Sulfopropyl (SP) / Methyl sulfonate (S): Strong cation exchangers ($-\text{SO}_3^-$).
• Anion Exchangers: Possess positively charged groups that bind anions:
• DEAE-Sepharose: Diethylaminoethyl, a weak anion exchanger ($-\text{CH}_2\text{CH}_2\text{N}^+\text{H}(\text{CH}_2\text{CH}_3)_2$).
• Q-Sepharose: Quaternary ammonium, a strong anion exchanger ($-\text{CH}_2\text{N}^+(\text{CH}_3)_3$).
• Conclusion: Resins (C) and (D) only are cation exchangers.

Correct option: (4) (C) and (D) only.

• Phase II Detoxification Reactions of Xenobiotics:
• Phase II reactions are conjugation reactions that attach an endogenous hydrophilic molecule to a functional group created in Phase I, forming water-soluble conjugates for excretion:
• Methylation: Catalyzed by methyltransferases using $S$-adenosylmethionine (SAM).
• Amino Acid Conjugation: Conjugation with glycine or glutamine (e.g., benzoic acid to hippuric acid).
• Glutathione Conjugation: Catalyzed by glutathione $S$-transferases (GSTs) utilizing reduced glutathione (GSH), ultimately excreted as mercapturic acids.
• Hydroxylation: A Phase I functionalization reaction catalyzed primarily by Cytochrome P450 monooxygenases.
• Conclusion: Reactions (A), (B) and (C) only are Phase II reactions.

Correct option: (1) (A), (B) and (C) only.

• Reactive Nitrogen Species (RNS): Nitrogen-containing free radicals and reactive molecules:
• Nitric Oxide ($\cdot\text{NO}$): A free radical synthesized from L-arginine by nitric oxide synthases (NOS).
• Peroxynitrite ($\text{ONOO}^-$): A highly reactive and damaging oxidant formed by the diffusion-controlled reaction of nitric oxide with superoxide:

• Reactive Oxygen Species (ROS):
• Superoxide ($\text{O}_2^{\bullet -}$) and (C) Hydroxyl Radical ($\cdot\text{OH}$) are primary reactive oxygen species (ROS) containing oxygen without nitrogen.
• Conclusion: Therefore, (B) and (D) only are reactive nitrogen species.

Correct option: (4) (B), (D) only.