# DBT JRF 2020 — Question 37

Exam: DBT JRF 2020 · Section: B · Topic: Biotechnology · Difficulty: Hard

## Question

Which of the following is a chemotherapeutic drug obtained from marine source?

## Options

- **A.** trabectedin
- **B.** avastin
- **C.** abraxane
- **D.** adriamycin

## Answer

Option A

## Explanation

When an enzyme is immobilised on an anionic (negatively charged) carrier (e.g. CM-cellulose, polyacrylic acid beads): Protons ( $\text{H}^+$ ) are attracted INTO the negatively charged microenvironment of the carrier (Donnan equilibrium effect). As a result, the local pH at the enzyme surface is LOWER than the bulk solution pH. To maintain optimal enzyme activity, the bulk pH must be raised to compensate. This makes the apparent pH optimum shift to a HIGHER pH compared to the free enzyme in solution. This is the partitioning effect — differential distribution of ions between the microenvironment and bulk. The opposite occurs with cationic carriers (local pH higher than bulk, apparent optimum shifts lower).

Source: https://mypyqbuddy.com/questions/which-of-the-following-is-a-chemotherapeutic-drug-6a05a8a02adafec47029323d