The trace metal present in insulin is

Which of the following compounds will form a zwitterion?

Which of the following amino acids contains a heterocyclic ring in its side chain $(R)$ group?

Which of the following amino acids has the lowest iso-electric point $(pI)$?

Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a protein in its native form is subjected to a physical change like a change in temperature or a chemical change like a change in $pH$,denaturation of proteins takes place. Explain the cause.

In an alkaline medium,glycine predominantly exists as/in a/an