Why Will Gly-Met-Gly React with Cyanogen Bromide, but Gly-Cys-Gly Will

question 44

Multiple Choice

Why will Gly-Met-Gly react with cyanogen bromide, but Gly-Cys-Gly will not react with cyanogen bromide?
I. There would be a highly strained four-membered ring intermediate in the case of cysteine.
II. After the addition of the thiol of cysteine to the cyano-group, a stable thioether will be formed, which does not react any further.
III. After the addition of the thiol of cysteine to the bromo-cation, a stable thioether will be formed, which does not react any further.
IV. Cysteine cannot form a stable bromonium-ion intermediate.

• A) I and II are correct
• B) II and III are correct
• C) I and III are correct
• D) II and IV are correct

---

Definitions:

Multi-Stage Model

A conceptual framework that describes a process or phenomenon as occurring in distinct phases or stages over time.

Reaction

The process of responding to internal or external stimuli, which can involve physical, emotional, or intellectual responses.

Denial

A psychological defense mechanism where a person refuses to accept reality or facts, hence avoiding dealing with painful feelings.

Learning Organization

Describes an organization that facilitates the learning of its members and continuously transforms itself to better respond to changes in the environment.