Digestion, Absorption and Metabolism of proteins

The dietary proteins are formed by long chains of amino acids bound together by peptide linkages

Diet containing protein are

Wheat        -      Glutenin, gliadin

Milk             -     Casein, albumin, lactalbumin and myosin

Egg              -      Albumin and vitelin

Meat            -      Collagen, albumin and myosin

Digestion of proteins

The enzymes responsible for digestion of proteins are called proteolytic enzymes

Mouth                     -  No digestion

Stomach                -  Pepsin is the only proteolytic enzymes in gastric juice

                                     Rennin is also present in gastric juice

                                     But rennin is absent in human

SI                             -  Most of the proteins are digested in SI  by photolytic enzymes

Pancreatic juice   - Trypsin, chymotrypsin and carboxy poptidases

                                     These break down the bonds of the protein molecules

Succus Entericus   -DI, tri and amino peptidases

Absorption of protein

The final products of protein digestion are the amino acids which are absorbed into blood from intestine

The levo amino acids are actively absorbed by means of sodium co- transport, whereas the dextro amino acids are absorbed by means of facilitated diffusion

It contains di, tri , amino peptidases

 

DIGESTION OF PROTEINS

                                                    

AREA	JUICE	ENZYME	SUBSTRATE	END POINT
MOUTH	SALIVA	NO	PROTEOLYTIC	ENZYME
STOMACH	GASTRIC JUICE	PEPSIN	PROTEINS	PROTEOSES PEPTONES
SMALL INTESTINE	PANCREATIC JUICE SUCCUS ENTERICUS	TRYPSIN CHYMO TRYPSIN CARBOXY PEPTIDASES  A & B DIPEPTIDASES TRIPEPTIDASES AMINO PEPTIDASES	PROTEOSES PEPTONES DIPEPTIDES TRIPEPTIDES POLYPEPTIDES DIPEPTIDES TRIPEPTIDES LARGE POLYPEPTIDES	DI, TRI  & POLYPEPTIDES AMINO ACIDS AMINO ACIDS