# DBT JRF 2020 — Question 40

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

## Question

The amino acid residue with the least preference for any quadrant in the Ramachandran map is

## Options

- **A.** serine
- **B.** valine
- **C.** alanine
- **D.** glycine

## Answer

Option D

## Explanation

Leuconostoc mesenteroides NRRL B-512F (and B-512(F)) is the primary industrial organism for dextran production. Dextran is a branched polysaccharide: $\alpha$ -1,6-linked glucan backbone with $\alpha$ -1,2, $\alpha$ -1,3, and $\alpha$ -1,4 branch points. Produced by the enzyme dextransucrase from sucrose: $n$ sucrose $\rightarrow$ dextran $+ n$ fructose. Industrial applications: Sephadex® gel filtration media (cross-linked dextran); clinical plasma volume expanders (Dextran 40, Dextran 70); drug delivery carriers; food thickeners. Molecular weight can be controlled by reaction conditions. Streptomyces olivaceus produces erythromycin; Bacillus thuringiensis produces Bt toxin; Bacillus polymyxa produces polymyxin antibiotics.

Source: https://mypyqbuddy.com/questions/the-amino-acid-residue-with-the-least-preference-6a05a8a02adafec470293240