Questions: For a short peptide:nAsp-Tyr-Gly-Asn-CysnWhich amino acid is the amino ( N -)terminal amino acid?nTyrnCysnGlynAsnnAsp

The answer is the last one (E): Asp.

Explanation for each option:

• Tyr: Tyrosine is the second amino acid in the sequence, not the N-terminal.
• Cys: Cysteine is the fifth amino acid in the sequence, not the N-terminal.
• Gly: Glycine is the third amino acid in the sequence, not the N-terminal.
• Asn: Asparagine is the fourth amino acid in the sequence, not the N-terminal.
• Asp: Aspartic acid is the first amino acid in the sequence, making it the N-terminal amino acid.

Summary: In a peptide sequence, the N-terminal amino acid is the one at the beginning of the sequence. In this case, Asp (Aspartic acid) is the first amino acid, making it the N-terminal.