Lab 4 - Exam. of E of digestion Flashcards
Degradation of N-compounds
Begins in stomach.
-Ru: forestomach by symbiotic microbes. Urease splits urea into NH3, which is a N-source for microbial protein synthesis.
Proteases
Protein-degrading E. 1.Endopeptidases: split proteins inside the chain 2.Exopeptidases: -aminopeptidases: split N-term. -carboxypeptidases: split C-term. Not S-specific.
Degradation of protein
1.Stomach. Ru: forestomach. Pepsin.
Calfs: Rennin prod. in abomasum.
2.Pancreas: Trypsin
3.Exopeptidases
Rennin
- Also called?
- Criterias to function as E
- Function
- Chymosin.
- Presence of Ca2+ in slightly acidic pH.
- Low degree hydrolysis. Degrade casein(milk)->paracasein. Clotting of milk.
Pepsine
- Prod?
- Function?
- HCl in stomach turn inactive pepsinogen to active pepsin.
- Provide optimal pH for E. Split peptide bonds in Phe and Leu.
Trypsin
- Prod.?
- Function?
- Opt.pH?
- Enteropeptidase prod. in small intestines, turn inactive trypsinogen prod. in pancreas, to active trypsin.
- Split peptide bonds in Arg and Lys.
- 7-9
Degradation of carbohydrates
- Some sp, eg. pig: Begins in mouth by amylase from saliva.
- In stomach low pH (HCl)-inhibits starch hydrolysis.
- Amylase from pancreas and small intestines finish starch hydrolysis.
Degradation of fats and oils
- By?
- Absorption?
- What increases their degradability?
- By lipase prod. in pancreas and intestinal wall.
- Simple fats absorbed as 2-monoacyl glycerol, or as fatty acids and glycerol.
- Bile salts increase water solubility of fats and thus their degradability by enzymes.
Lipase
- Function?
- Opt.pH?
- What can promote it´s function?
- Splits glycerol in fatty acids.
- 7.8
- Ca2+ ions
Which E is prod. by…
- Oral cavity
- Stomach
- Rumen
- Abomasum(calf)
- Pancreas
- Small intestines
- Salivary amylase
- Pepsin
- Urease
- Rennin(chymosin)
- Pancreatic amylase and lipase, trypsin, chymotrypsin
- Lipase, enteropeptidase
Materials used in “detection of labferment (rennin, chymosin)”?
- Milk
- Rennin sol.
- Ammonium oxalata
- CaCl2
- Water bath at 37 degrees
Materials used in “measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?
- Diluted blood plasma
- Pepsin sol.
- HCl
- Na2CO3
- Trichloroacetic acid
- Spectrophotometer
- Water bath at 37 degrees
Role of tubes in “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?
1.Dist. water and pepsin: Blank for spectrophotometry All others have blood plasma and pepsin 2.HCl: pH≈1.5 3.Dist.water: pH≈7 4.Na2CO3: pH≈10
How do we measure the pepsin activity?
Measuring amount of tyrosine and thryptophan - by Folin´s method - pos.
How does TCA react in “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?
It ppt. the undigested proteins and polypeptides. But oligopeptides and A.a. prod. by enzymatic hydrolysis of proteins are soluble in TCA.
Materials used in “Digestion of milk fat by lipase from pancreas”?
- Pancreas extract (drug)
- Boiled milk
- 0.2M phospate buffer, pH=7.8
- 0.21M ammonium oxalate sol.
- Bile or cholic acid (replaced by detergent)
- Phenolphtalein
- NaOH
- Water bath at 37 degrees
Background of “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?
The liberated fatty acids (splitted from glycerol by Lipase) causes acidic pH of the medium. This can be titrated by alkaline and the amount can be estemated by a calibration curve.
Materials used in “Measuring the trypsin activity”?
- Pancreatic extract (drug)
- Dilated blood plasma
- TCA
- Folin´s 1+2
- Phosphate buffer (0.2M, pH7.8)
- Spectrophotometer
- Water bath at 37 degrees
Background of “Measuring the trypsin activity”?
How will the activity be measured?
TCA ppt. undigested proteins and polypeptides. But oligopeptides and A.a. prod. by the E hydrolysis of proteins, are soluble in TCA.
Activity measured by amount of tyrosine and tryptophan-Folin´s method-pos.
All labtests
- Detection of labferment (rennin, chymosin)
- Digestion of milk fat by lipase from pancreas
- Measuring the pepsin activity, dependence of the velocity of the R on the actual pH
- Measuring the trypsin activity
