Peptide bonds

Question 1

Peptides

Answer 1

Short polymers of amino acids in a peptide chain up to 100 amino acids

Question 2

Proteins

Answer 2

long polymers of amino acids in a polypeptide chain usually > 100 amino acids

Question 3

Peptide bonds

Answer 3

Amino acids bound together by them

Net reaction for peptide bond formation is a condensation reaction between the alpha-carboxyl group of 1 amino acid and the alpha-amino group of the next producing one molecule of water
Amino acids are covalently linked to one another by the formation of peptide bonds. These bonds form amide linkages. The linkage of 2 amino acids by a single peptide bond creates a dipeptide etc.

Question 4

Depicting peptides

Answer 4

By convention when depicting peptides, the free amino group is written on the left hand side and is called the N-terminal amino acid or the amino terminus.
The free carboxyl group is written on the right hand side and is called the C- terminal amino acid or the carboxyl terminus.

Question 5

Where does the reaction take place

Answer 5

Ribosome

Catalysed by the peptide transferase enzyme component

Question 6

Peptide bond hydrolysis

Answer 6

Exopeptidases (exoproteases)- catalyse the hydrolysis of either the amino terminal peptide bond or the carboxyl terminal

Endopeptidases (endoproteases)- catalyse the hydrolysis of peptide bonds inside the peptide chain and are usually fairly specific

Question 7

Isopeptide bonds

Answer 7

formed between side chain amino group of Lys and the side chain of Asp, Glu, Asn, Gln, an internal peptide bond or a terminal alpha-carboxyl group