Protein Study Flashcards
what are proteins?
essential components of animal tissue
chemically, amino acids consists of?
alpha carbons
amino groups
carboxyl group
side chains
how many AA are there
300
how many AA used for protein synthesis
20
2 isomeric forms AA can exists
D and L isomers
key points of L-isomer
only one used in proteins
used nationally
D made into L to make protein
proteins are macromolecules of?
amino acid chain
Amino acids classified based on
Structure
Essentiality
Polarity
Electrical Charge
what is important about each characteristics
structure = distinct side chain Essentiality = dietary requirements Polartiy = non-polar v polar
Structure and Essentiality similarities
side chain determines if AA are synthesized by mammalian cells
Polarity
when AA interact with water at physical pH
electrical charge
charge of amino acid in aqueous solution at physical pH
what synthesizes amino acids
microbes
diet (plants)
what doesn’t synthesizes amino acids
animals
amino acids essential and non-polar
valine methionine leucine tryptophan isoleucine phenylalanine
amino acids nonessential and nonpolar
glycine
alanine
proline
amino acids essential and polar
arginine
histidine
lysine
theronine
amino acids nonessential and polar
tyrosine cysteine serine aspartate asparagine glutamate glutamine
amino acids that are branched
valine
leucine
isoleucine
sulfur containing amino acids
methionine
cysteine
amino acids considered aromatic
trytophan
phenylalanine
which amino acids transport nitrogen
aspartate
glutamate
what amino acid in pigs and chicken with corn
Lysine
amino acids not branched
Theronine
what is wrong with Proline?
digestive issues due to Nitrogen side chain
what are essential amino acids?
required in diet and mammalian cells can’t synthesize proper amounts
what are limiting amino acids?
EAA that are limited in diet
what are non-essential amino acids?
not required in diet due to mammalian cells making sufficient amounts
why is arginine considered semi-essential?
can be synthesized in body NOT in proper amounts
limiting amino acids in ruminants
Methionine
limiting amino acids in pigs
Lysine
what are protein chains made of?
amino acids
amino acids linked by?
peptide bonds
what are dipeptides?
2 amino acids linked
what are polypeptides?
greater than 10 amino acids linked
what are protein synthesis based on
genetic code
what’s transcription?
DNA code copied to mRNA
what’s translation?
mRNA used to assemble an amino avid chain
what biological properties of protein does genetic code determine
AA protein contain
AA sequence
length of AA chain
spatial relationship of AA within protein
what protein is made with high levels of cystine
keratin
ex. hair
4 levels of structural organization in proteins
Primary
Secondary
Tertiary
Quartenary
what does the primary structure consists of
sequence of amino acids linked by peptide bonds
what does secondary structure consists of
coiling of folding polypeptide chains to alpha-helix/beta-pleated sheets from H bonds
what does the tertiary structure consists of
3-D folding of chain by H bonds and electrostatic attractions
what does the quartenary structure consists of
protein macromolecules formed by polypeptide chains by H bonds and electrostatic attraction
how are proteins classified
based on composition, solubility, nutritive value, shape, size and function
microbes provide how much protein for ruminants
50 - 80%
what is the ultimate goal of protein digestion?
- pieces of food converted to smaller digestible portions
- hydrolysis of peptide bonds to produce free AA
what does digestive enzymes do?
break peptide bonds
name of digestive enzymes secreted as inactive pro-enzymes
zymogens
what is exopeptidases?
cleave amino acids at terminal end of protein molecules
what is endopeptidases?
hydrolyse peptide bonds within primary protein structure
Characteristics of HCl in protein digestion
- released from parietal cells
- pH = 1.6 - 3.2
- Denatures 4, 3 and 2 structures
Characteristics of Pepsiogen in protein digestion
- released from chief cells
- works with HCl to become pepsin
Characteristics of Pepsin in digestion
- Endopeptidase
- cleaves side of amino side of aromatic AA
active form?
inactive form?
active = pepsin inactive = pepsinogen
pH of small intestine in non-ruminant protein digestion
7 - 8
pancreatic enzymes secreted in small intestine of non-ruminant
Trypsinogen Chymotrypsinogen Procarboxypeptidase Proelastase Collagenase
Intestinal brush border enzymes secreted
Aminopeptidases
Dipeptidases
Trypsinogen activated by and converted to
Activated = Enteropeptidase Converts = Trypsin
Chymotrypsinogen activated by and converted to
Activated = Trypsin
Converted –> Chymotrypsin
Procarboxypeptidase activated by and converted to
Activated = Trypsin
Converted –> Carboxypeptidase
where does aminopeptidase cleave
Nitrogen terminal of AA
dipeptidases cleave what?
dipeptides
what are proteins broken down to?
- Tripeptides
- Dipeptides
- Free AA
Characteristics of Trypsin inhibitors?
- small proteins & peptides
- inactivated by heat
- block digestion of proteins
- found in plants, organs and fluids
Ruminally Degradable Proteins
proteins available to the rumen microbes
Ruminally Undegradable Protein
protein that escapes rumen fermentation and goes to small intestine
Non Protein Nitrogen
not true protein providesa source of Nitrogen
Microbes break down dietary proteis
- amino acids
- NH3
- VFAs
- CO2
Factors that affect ruminal degredation
- Heat Treatment
- Rate of Passage
- N and S availability
- Energy availability
