Digestion of Casein by Trypsin

1. Digestion of Casein by Trypsin ■ Proteases Enzymes: Enzymes that catalyze the hydrolysis of pepide bonds of proteins.

2. Digestion of Casein by Trypsin ■ Exoproteases: liberate amino acids by breaking peptide bonds starting from the end of the polypeptide chain. -H2O

3. Digestion of Casein by Trypsin ■ Endoproteases: break down peptide bonds from the interior of the polypeptide chain. e.g. Trypsin and Pepsin.

4. Trypsin A endoprotease enzyme found in the pancreatic juice which catalyzes the hydrolysis of peptide bonds formed from the carboxyl groups of basic amino acids, L-Arginine L-Lysine

5. Pepsin is an endoprotease found in the stomach which catalyzes the hydrolysis of peptide bonds between aromatic amino acids; Phenylalanine Tyrosine Tryptophan

6. *Principle Trypsin Casien Free amino groups ~NH3 + H.CHO ~NH.CH2O + H (monomethylol)

7. 60 5 55 10 50 45 15 40 20 35 25 30 Tube # 1 2 3 4 1% 0.8% 0.6% 0.05% 30 min. 37°C Casien (ml) 1 1 1 1 Trypsin (ml) 0.2 0.2 0.2 0.2 TCA 12% (ml) 1 1 1 1 5 min at 3000 rpm

8. 1 1% Va.a. 0.1N NaOH 2 drops ph.ph. Supernatant VNaOH 5 ml 40% HCOOH 2 Va.a. 0.8% VNaOH 3 0.6% Va.a. VNaOH 4 0.5% Va.a. VNaOH

9. * Calculations ( N × V ) a.a. = ( N `× V `) NaOH Na.a. = ( N `× V `) NaOH Va.a. Samar A. Damiati