Protein Metabolism Flashcards
What is a peptide?
short chain of AA (less than 50)
What is a protein?
a long chain of AA
-sequence will determine shape and function
What is an essential AA?
-cant be synthesize by the body of cant be synthesized at a high enough rate to support the need
-required in diet
What is a nonessential AA?
cant be synthesized at a high enough rate to support the body’s needs
-does not need to be included in diet
What are conditionally essential AA?
non essential AA may become essential if the rate of synthesis is not high enough to meet the demand
What is a semi essential AA?
synthesized from essential AA
-if there is not enough of the essential AA precursor in the diet, these AA become essential
What are the essential AA?
- Phenylalanine
- Valine
- Threonine
- Tryptophan
- Isoleucine
- Methionine
- Histidine
- Arginine
- Lysine
- Leucine
(PVT TIM HALL)
What are the non essential AAs?
- Cysteine
- Alanine
- Asparagine
- Aspartate
- Tyrosine
- Serine
- Glycine
- Glutamine
- Glutamate
- Proline
What are the semi essential AAs?
Cysteine and Tyrosine
What is cysteine synthesized from?
methionine
-need to include enough methionine in diet to meet the requirement for methionine needs + the synthesis of cysteine
-if include cysteine in the diet, this will have a sparing effect on methionine and decrease methionine requirement
What is tyrosine synthesized from?
phenylalanine
-need enough in diet to meet needs + synthesis
-sparing effect
Protein digestion in the stomach deals with?
-HCl
-Pepsin
What does the HCL do?
denatures protein
What does the pepsin do?
pepsinogen is activated by HCL to be pepsin
then pepsin breaks down protein into long peptide chains
How does protein digestion work in the small intestine?
-cholecystokinin is secreted when chyme enters the duodenum
-CCK acts on pancreas to secrete digestive enzymes
etc
What digestive enzymes does the pancreas secrete after CCK acts on it?
-trypsinogen
-chymotrypsin
-procarboxypeptidase
What is secreted by the brush border?
enterokinase
-activates trypsinogen to trypsin
What does trypsin activate?
chymotrypsinogen to chymotrypsin & procarboxypeptide to carboxypeptide
What breaks down large peptides into oligopeptides? (<10AA)
trypsin, chymotrypsin, & carboxypeptidase
What does aminopeptidase (secreted by brush border) do?
breaks down oligopeptides into tripeptides, dipeptides, and free AAs
What do microbes synthesize?
microbial protein from dietary protein and AA
Microbial protein leaves rumen for
digestion in abomasum and s.i.
Na+ dependent AA transport system
transports Na+ into cell w/ the amino acid
Na+ independent AA transport system
transports AA into the cell
Peptide transport (Tri and Di-peptide)
-transport di- or tri- peptide w/ a H+ into the cell
-cellular aminopeptidases breakdown di- and tri- peptides into free AA
-free AA leave the cell via AA transporters and enter the hepatic portal system
Functions?
-maintain body structure
-facilitate mobility
-transport
-metabolism
-regulation
-immune regulation
What is nitrogen balance?
measure N intake & excretion
What is positive nitrogen balance?
N intake exceeds N excretion
What is nitrogen equilibrium?
N intake = N excretion
-indicates maintenance
What is negative nitrogen balance?
N intake less than N excretion
-geriatric animals/ disease states
What is dynamic protein turnover?
continual degradation and resynthesis of body protein