5.
The uncommon amino acid selenocysteine has an R group with the structure –CH2—SeH with a pKa of approximately 5. In an aqueous solution, pH=7.0, selenocysteine would:
A:
Be fully ionized zwitterion with no net charge
B:
Be nonionic
C:
Never be found in a protein
D:
Not be optically active
The answer is:
A
