Proteins

Proteins

Digestion and absorption

Proteins

HClpepsin

Exopeptidases Enterokinase

Bicarbonate Pancreatic proteases

Proteins

Active enzyme

Synthesized as zymogens(proenzymes)

Proteolytic enzymes

Proteins

Proteolytic enzymes

Exopeptidases • Polypeptidases

– Aminopeptidases– carboxypeptidases

• Tripeptidases• Dipeptidases

Endopeptidases

• Pepsin• Trypsin• Chymotrysin• Elastase

Proteins

Stomach

Pepsinogen

Pepsin

H+

Proteins

Exocrine pancreas

CCK

Zymogens

Secretin

Proteins

Activation of pancreatic zymogens

Trypsinogen

Trypsin

Chymotrypsinogen chymotrypsin

Proelastase Elastase

Procarboxypeptidase Carboxypeptidase

ProteinsProteins

Trypsin

• Ariginine• Lysine

Dr Fatahiya Kashif

ProteinsProteins

Chymotrypsin

• Acidic • Hydrophobic

ProteinsProteins

Elastase

• Alanine • Glycine • Serine

ProteinsProteins

Carboxypeptidase

• Hydrophobic • Basic

ProteinsProteins

Intestinal enzymes

• Exopeptidases – Brush border – Within the cell

• Enterokinase

Proteins

Aminopeptidase

ProteinsProteins

• …AND ALLAH DOTH INCREASE IN GUIDANCE THOSE WHO SEEK GUIDANCE; AND THE THINGS THAT ENDURE, GOOD DEEDS, ARE BEST IN THE SIGHT OF THY LORD, AS REWARDS, AND THE BEST IN RESPECT OF EVENTUAL RETURNS.

76-MARYAM; AL-QURAN

Proteins

Absorption of amino acids

ProteinsProteins

Transport systems

• Free amino acids– Sodium linked secondary transport

• Di and tri peptides– H+ linked transport system

• Portal vein– Liver– General circulation

Proteins

Na+3Na+

2K+

Proteins

Na+

Proteins

Na+

Proteins

Na+

Proteins

Na+

Proteins

Na+

Proteins

Gamma glutamyl cycle

Glu Cys Gly Glu

Proteins

Gamma glutamyl cycle

Cys

Gly

Glu 5-oxoproline

Proteins

Gamma glutamyl cycle

Cys

Gly

5-oxoproline

ATPADP

Glu

Proteins

Gamma glutamyl cycle

Cys

Gly

ATPADP

Glu

Proteins

Gamma glutamyl cycle

Gly

ATPADP

Glu Cys

Proteins

Gamma glutamyl cycle

Glu Cys Gly

Cys Gly Glu

Proteins

GLUTATHIONE

GSH GSH GSSG

Proteins

Digestion and absorption of proteins

Disorders

ProteinsProteins

Disorders

• Cystic fibrosis

• Cystinuria

• Hartnup disease

• Kwashiorkor

Proteins

Cystic Fibrosis

ProteinsProteins

Cystic Fibrosis

• Defect in function of chloride channels in pancreatic secretory ducts

• Inspissation of pancreatic exocrine secretions• Eventual obstruction of ducts

ProteinsProteins

Cystic Fibrosis

• Recurrent infections

• Poor growth

• Foul smelling bulky stools

ProteinsProteins

Cystic Fibrosis

• Commercial enzyme preparations

ProteinsProteins

Hartnup disease

• Autosomal recessive disorder

• Transport of neutral aminoacids across both intestinal and renal epithilial cells

Dr Fatahiya Kashif

Proteins

Hartnup disease

Essential • Isoleucine• Leucine• Phenylanaline• Threonine • Tryptophan• Valine

Nonessential • Alanine • Serine• Tyrosine

ProteinsProteins

Hartnup disease

C/F• Asymptomatic• Pallegra like symptoms• Neuropsychiatric

Treatment• Niacin

ProteinsProteins

Cystinuria

Defect in absorption of• Cystine• Ornithine• Arginine• LysineC/F• Appearance of these amino acids in urine• Cystine stones Treatment • Oral hydration

ProteinsProteins

Kwashiorkor

• Deficiency of protein in diet which is adequate in calories

C/F• Muscle wasting• Edema