94. Trp florescence can be used to study protein folding and unfolding. Which properties of
Trp are critical in ensuring that this can be used for studying the process?
(a) Trp in the only amino acid present in most of the proteins,
(b) Trp is a better hydrogen bond acceptor than most other amino acids,
(c) Trp is a positively charged amino acid,
(d) Trp is an environment sensitive fluorophore which is typically buried in a foldedprotein

Detailed Explanation:
Protein folding is a dynamic process crucial for proper function, and its study is essential in fields ranging from enzymology to disease research. One powerful tool for observing protein folding and unfolding is tryptophan (Trp) fluorescence.

Why is Trp useful?

Tryptophan is an intrinsically fluorescent amino acid, and its fluorescence properties are uniquely sensitive to its local environment:

• In a folded protein, Trp residues are often buried within the hydrophobic core, shielded from water.

• Upon unfolding, these Trp residues become exposed to the aqueous environment, which causes a change in fluorescence intensity and emission wavelength.

These changes in fluorescence can be monitored in real-time, providing insights into the conformational changes of the protein during folding/unfolding.

Evaluating the Options:

• (a) Trp is the only amino acid present in most proteins
   Incorrect. Proteins contain many types of amino acids; Trp is just one among twenty.

• (b) Trp is a better hydrogen bond acceptor than most other amino acids
  Not the reason Trp is used in fluorescence studies.

• (c) Trp is a positively charged amino acid
  Trp is actually neutral at physiological pH.

• (d) Trp is an environment-sensitive fluorophore which is typically buried in a folded protein
  Correct. This property makes Trp ideal for monitoring structural changes in proteins.

Final Answer:

(d) Trp is an environment-sensitive fluorophore which is typically buried in a folded protein