Question

Which is true about Trypsin?

		It does not affect any peptide bonds.
		It hydrolyzes all peptide bonds.
		It hydrolyzes peptide bonds to leucine and phenylalanine.
		It hydrolyzes peptide bonds to arginine and lysine.

Answer 1

Trypsin hydrolyzes the peptide bonds to arginine and lysine.

Trypsin is a serine protease from PA clan superfamily,found in the digestive system of many vertebrates,where it hydrolyzes the proteins.Trypsin is formed in the small intestine when it proenzyme form,the trypsinogen produced by the pancrease,is activated.Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or argine except when either is followed by proline.It is used for numerous biotechnical processes.The process is commonly referred as trypsin proteolysis or trypsinisation,and proteins that have been digested with trypsin are said to have been trypsinized.

In the duodenum,trypsin catalyses the hydrolysis of peptide bonds,breaking down protein into smaller peptides.The peptide products are then further hydrolysed into amino acids via other proteases,rendering them available for absorption into the blood stream.Trypsin digestion is necessary step in protein absorption.

In small intestine,the enzyme enteropeptidase activates trypsinogen into trypsin by proteoytic cleavage.

The asperate residue located in the catalytic pocket of trypsin is responsible for attracting and stabilizing positively charged lysine and/or arginine and thus responsible for the specificity of the enzyme.This means that trypsin predominately cleaves proteins ate the carboxyl side of the amino acids lysine and arginine except when either is bound to a C-terminal proline,although large scale mass spectometry data suggest cleavage occurs even with proline.Trypsin is considered an endopeptidase,i.e cleavage occurs within the polypeptide chain rather than at the terminal amino acids located at the end of polypeptides.