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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