The tripeptide hormone present in most living cells is...

$A$ tetrapeptide is made of naturally occurring alanine,serine,glycine,and valine. If the $C$-terminal amino acid is alanine and the $N$-terminal amino acid is chiral,the number of possible sequences of the tetrapeptide is $....$

Which of the following is generally water insoluble?

The bond that determines the secondary structure of proteins is or secondary structure of protein is due to

The prosthetic group of haemoglobin is

Choose the correct option for structures of $A$ and $B,$ respectively.