Protein Matebolis Flashcards
Essential and NON essential amino acids
- NON-ESSENTIAL: the organism (can or can’t?) synthesize the ____ analog.
- ESSENTIAL: the organism (can or can’t ?) synthesize their carbon skeletons, so must ______
a-keto
Can
Can’t
obtain these amino acids in the diet.
Essential must get in diet Non-essential mammals synthesize
- __* (children only)
- ____* (children only)
- list the rest
Arg
His
Ile •Leu •Lys •Met •Phe •Thr •Trp •Val
•Dietary proteins (can or cannot?) be absorbed directly from the intestine.
Cannot
To be absorbed, dietary protein must be digested into small simple molecules (______) which are easily absorbed into the small intestine.
amino acids
Protein digesting enzymes are produced in the (active or inactive ?) form (_____) in the gastro-intestinal tract to prevent ________ of _____
They are activated when protein from food is to be digested.
Inactive
zymogen
digestion of the tissue.
Steps in Protein digestion
•Protein digestion starts in the _______.
stomach
Steps in Protein digestion
The ___ juice produced in the stomach contains _____ and _____
Pepsinogen is activated to pepsin by ____.
- Further activation of pepsinogen occurs when the pepsin produced cleaves a ____ residue peptide from the _____ terminal end of pepsinogen.
- Pepsin hydrolyses peptide bonds between ____ amino acids and ____ amino acids in the protein.
- The partially digested protein moves into the _____
Gastric
pepsinogen and HCl.
HCl
forty four ; amino
aromatic; acidic
small intestine.
Steps in Protein digestion contd.
•The pancreatic juice produced by the pancreas contains inactive protein digesting enzymes namely ______,______,_____
trypsinogen, chymotrypsinogen and procarboxy-peptidase.
Trypsinogen is activated to trypsin by ______ from ____ cells.
Further activation of trypsinogen occurs as the trypsin already formed cleaves the peptide bond between _____ and ______ in a ____peptide.
•Trypsin hydrolyzes peptide bonds where ___ amino acids (Arg, Lys, His) in the polypeptide chain contribute the ______ group.
enteropeptidase; duodenum
lysine and isoleucine; octa
basic; carboxylic
Steps in Protein digestion contd.
•Chymotrypsinogen is activated by ____ to __-chymotrypsin by removing a short peptide from it
trypsin; b
Steps in Protein digestion contd
β-chymotrypsin is activated to a-chymotrypsin by _______ by removing another short peptide from it.
α-chymotrypsin cleaves peptide bonds where ______ amino acids contribute the ______ group.
chymotrypsin
aromatic; carboxylic
Steps in Protein digestion contd
Procarboxy-peptidase is activated by ____ to carboxypeptidase.
The active enzyme hydrolyses ___ peptide linkage with _______ group.
trypsin
end; free carboxylic
Steps in Protein digestion contd
Succus entericus produced by ______ cells contains _________ and _____
intestinal mucosa
aminopeptidase and dipeptidase.
Aminopeptidase splits off ____ amino acid with _____ group.
Dipeptidase hydrolyses _____ to _____ which are the end products of protein digestion.
terminal
free amino
dipeptides to free amino acid
SPECIFIC ROLES IN PROTEIN DIGESTION
1.Digestion in the stomach
Protein digestion begins in the stomach by gastric juice.
B.Role of gastric HCL
●It causes ______ of proteins
●It converts proteins to _______, which are easily digested.
●It activates pepsinogen to ___.
●It makes ___ in the stomach suitable for the action of pepsin.
denaturation
metaproteins
pepsin
pH
Pepsin
- It is an (endo or exo?) peptidase acting on ____ peptide bond in which amino group belongs to aromatic amino acids e.g phenylalanine, tyrosine and tryptophan.
- It is secreted in an inactive form called pepsinogen.
- Its optimum pH is __-___
- It is activated by ____ then by _____.
Endo
central
1.5-2.2.
HCL
autoactivation
Renin
•It is a ____________ enzyme.
•It is present in stomach of _____ and ______
•Its optimum pH is ___.
•It acts on casein converting it to (soluble or insoluble?) ____, which in turn binds ____ ions forming (soluble or insoluble?) ___________ which is then digested by ____
milk-clotting
infants and young animals.
4
Soluble; paracasein; calcium
Insoluble
calcium paracaseinate
pepsin
Gelatinase
It is an enzyme that _______ ———
The end products of protein digestion in the stomach are ————,———,——-
liquefies gelatin.
proteases, peptones and large polypeptides.
Digestion in the small intestine
Digestion of protein is completed in the small intestine by proteolytic enzymes present in _____ and _____ juices.
A. Trypsin
•It is an (endo or exo?) peptidase that hydrolyzes ____ peptide bond in which the carboxyl group belongs to ___ amino acids. E.g. arginine, lysine and histidine.
•It is secreted in an inactive form called ____.
•Its optimum pH is __
•It is activated by _____ enzyme then by _____.
pancreatic and intestinal
Endo
central; basic
trypsinogen
8
enterokinase
autoactivation
Chymotrypsin
•It is an (endo or exo?) peptidase that hydrolyze central peptide bond in which the carboxyl belongs to ____ amino acids.
•It is secreted in an inactive form called _____.
•It is activated by ___.
•Its optimumpH is __
Endo; aromatic
chymotrypsinogen
trpsin
8
Elastase
It is an (endo or exo?) peptidase acting on peptide bonds formed by ____,____,____
It is secreted in an inactive form called ____.
It is activated by ____.
It digests _____ and _____
Its optimum pH is ___.
Endo
glycine, alanine and serine.
proelatase
Trypsin
elastin and collagen.
8
Carboxypeptidase
•It is an ( endo or exo?) peptidase that hydrolyze terminal ( ______ ) peptide bond at the ___ terminus of the polypeptide chain.
•It is secreted in an inactive form called _____.
•It is activated by ____.
•Its optimumpH is ___.
Exo
peripheral
carboxyl
procarboxypeptidase
Trypsin
7.4
Intestinal juice
A. Aminopeptidase
•It is an ( endo or exo?) peptidase that acts on the ______ peptide bond at the ___ terminus of the polypeptide chain.
•It releases a single amino acid.
Exo
terminal
amino
Tripeptidase
It acts on ______.
It releases _____ and ____
Dipeptidase
It is acts on ______.
It releases _______
tripeptides
a single amino acid and dipeptide.
dipeptides
2 amino acids.
Protein Absorption
•it is an (active or passive?) process that needs energy
- It occurs in ______
- Absorption of amino acids is rapid in the ________ but slow in the ______
Active
small intestine
duodenum and jejunum
ileum.
Mechanism of amino acid absorption
There are two mechanism for amino acids absorption.
- _______________ system
- __________ transport system
Carrier proteins transport
Glutathione
Pathways for amino acid degradation
In animals, amino acids undergo _________ in three different metabolic circumstances:
- During the normal synthesis and degradation of cellular proteins, some amino acids that are released from protein breakdown and are _____________ undergo oxidative degradation.
- When a diet is rich in protein and the ingested amino acids __________, the surplus is catabolized
- During _________ or ______, when carbohydrates are either unavailable or not properly utilized, cellular proteins are used as ____.
oxidative degradation
not needed for new protein synthesis
exceed the body’s needs for protein synthesis
starvation or in uncontrolled diabetes mellitus
Fuel
amino acids (can or cannot?) be stored
Cannot
Reactions amino acids undergo
- Transaminations:
•catalyzed by ______;
•they are named according to their ______ substrates (ex: glutamate-aspartate aminotransferase).
•reaction Requires ______ and a _______ (eg ————)
aminotransferases
amino acid
an amino acid and a keto acid
alpha keto glutarate
Reactions amino acids undergo
- Decarboxylation: ____ of _____
- Racemization: interconversion of ____ and ___ forms.
- _____ and ———-e deamination
- ____lization
- Elimination and replacement reaction ___-carbon of amino acid
- Elimination and replacement reaction __-carbon of amino acid
Removal of carbondioxide
L- and D-
Oxidative and non-oxidative
Dealdo
β
Alpha
Excretion
There are 3 nitrogen waste excretion products of animals from amino acid degradation.
- ______
- 2) ____
- 3)_______
Ammonia (NH3 or NH4+)
UREA
URIC ACID
- Ammonia (NH3 or NH4+).
- _______ animals simply release it into the surrounding ____ where it gets diluted to non-toxic concentrations. Animals that do this are called ______.
- 2) UREA
- Most ______ (especially _____)
- —called _____.
- 3) URIC ACID
- _______ and ______ (the (black or white?) stuff: not very H2O soluble)
- —called _______.
Aquatic
water
AMMONOTELIC
terrestrial vertebrates; mammals; UREOTELIC
Birds & terrestrial reptiles
White; URICOTELIC
Neurotransmitters derived from amino acids include
_______, 5-hydroxytryptamine (serotonin), dopamine, norepinephrine, and epinephrine.
γ-aminobutyrate
Conversion of ______ to Niacin, tryptamine.
Role of ___,______,____,_____ as precursors for synthesis of folic acid and vitamin B12- one carbon metabolism.
Tryptophan
glycine, serine, glutamine, methionine
Some deficiencies and diseases associated with amino acids metabolism
These are in-born errors caused by blocks in some biochemical pathways due to an (heritable or inheritable?) enzyme deficiency.
- The blocked amino acid accumulate and may be directed into other pathways which results in the formation of __________
- The blocked amino acid appear in (little or large?) amounts in the urine of the person with the error.
inheritable
deleterious substances.
Large
aminoacidurias.
•Two types exist:_______ and _____ aminoacidurais.
overflow and renal
In overflow aminoacidurias
the plasma level of the amino acid involved is ______ due in part to _______ and the deficiency of ___________
•There such deficiencies like: _________,________,________,_______disease
excessively high
over production
metabolizing enzyme.
phenylketonuria, alkaptonuria, homocystinuria and marple syrup urine
In renal aminoacidurias
the renal tubules are unable to ________
•
•The amino acids are thus lost in ____.
•The two major deficiency states are _____ and ______ disease.
reabsorb some amino acids.
urine
cystinuria and hartnup
Phenylketonuria (PKU)
•Here the enzyme __________ is lacking as a result phenylalanine is directed to the production of deleterious acidic substances such as _________
- Occurs in one of every _____ birth.
- Clinical manifestation include severe ________,________, and _______
phenyl alanine hydroxylase
phenyl lactic acid.
10,000
mental retardation, convulsion and depigmentation (Albinism).
the most prevalent of the aminoaciduria is ????
Phenylketonuria
_____ leads to melanin pigments
DOPA
Clinical features of PKU
Baby goes from a normal infant to an idiot in _____ - very striking.
Epilepsy and seizures,__-__ months. Stops before ____.
EEG: abnormal pattern; injury in hypothalamus.
Behaviour:
Uncontrollable ___.
_______.
Hyperactive
one year
6-18
adulthood
temper
Irritable
Sypmtoms of PKU
•_________ odor of urine, which is caused by _______.
•Skin lesions: _____.
•Vomiting.
•Pigmentation: ~60% of patients with PKU are ___ and ___-eyed.
Musty (“mousey”) ; phenylpyruvate
eczema
blond and blue
Most PKU patients are blond and blue -eyed.
Why??
•The _____ of tyrosine by tyrosinase, which is the first step in formation of the pigment melanin, is ______ inhibited by the high levels of ______ present
hydroxylation
competitively
phenylalanine
Diagnosis of PKU
In urine: phenylalanine + FeCl3 _________ colour reaction.
Requires high concentrations of ______.
olive-green
phenylpyruvate
Treatment of PKU
Start as soon as possible!
The earliest treatment is started, the more ______ can be prevented.
Treatment should not be delayed beyond the ______ of life.
neurological damage
first month
IN PKU patients
Most natural protein contains phe – impossible to satisfy body’s protein without exceeding phe limit…so blood phe is maintained by feeding ______ amino acid preparations (low or high?) in phe.
Some natural foods are used as well that are low in phe: fruits, veggies, certain cereals.
synthetic
Low
In PKU PATIENTS
Tyrosine supplement: tyrosine is now an ____ amino acid; if low, L-tyrosine supplements are given.
10% of protein prescribed.
essential
tyrosine supplements alone will prevent mental retardation in classic PKU.
T/F
F
tyrosine supplements alone will not prevent mental retardation in classic PKU.
In a pku patient, how long should the low phe diet be used for
After ___: development of brain over. Low phe is maintained at least for _____
Continue throughout _____ or ___ to be safe
1 year; 4-5 years.
Adolescence
Life
Reversal of Biochemical Abnormalities in a pku patient that is under treatment
___ease in concentration of phe metabolites in urine.
____ skin,____ pigment.
Neurological signs: all improved; less restless, pay more attention, EEG normalized.
I.Q. depends on ______
Decr
Better
darker
time, age…
Maternal PKU
When women with PKU who are not on a low phenylalanine diet become pregnant, the offspring are affected with the “maternal PKU syndrome”: ______,_______,______ abnormalities in the fetus.
These developmental responses occur during the ______ of pregnancy. Thus, dietary control must begin ______
microencephaly, mental retardation, and congenital heart
first months
prior to conception
Alkaptonuria
- In this situation, the metabolism of phenylalanine and tyrosine is blocked at the stage of _____________
- ________ accumulate and appear in urine.
- The urine ____ on _____
homogentisic acid oxidase.
Homogentisic acid
darkens; standing
Excessive homogentisic acid causes damage to _____, ______ as well as precipitating as ______
cartilage
heart valves
kidney stones.
Homocystinuria
- Here the enzyme ________ is deficient
- As a result of ____ and its disulphide oxidation product homocystine accumulate and are secreted.
- This leads to ____ disorder.
- This also occurs in the absence of another enzyme _______ which breaks ______ to _____
cystathione synthetase
homocysteine
skeletal
cystathionase
cystathione to cysteine
Homocystinuria
•________+ ____—> Cystathione
____ enzyme is deficient
OR
Cystathione –> -> _______ + ______
_____ enzyme is deficient
Homocysteine ; serine
cystathione synthetase*
Homoserine + Cysteine
cystathionase*
Maple syrup urine disease
•This disorder involves ______ amino acids (___,____,___)
•The deficient enzyme is branched chain _____ and ________
•______ accumulates causing ____ and mental retardation.
•The disease is manifested by severe brain damage.
•Urine smells like ____.
•Few infants survive beyond the _____ of life
branched chain
valine, leucine, isoleucine
ketodecarboxylase and ketodehyrogenase.
Keto acids; ketosis
maple syrup
first year
Renal aminoacidurias
Cystinuria: the amino acid involved are the ___ amino acids- ____,____,____,____
These are thought to possess a common _______ in the renal tubules.
Failure of the transport system results in cystinuria.
Clinical effect includes ______ due mainly to presence of ____ which is very (soluble or insoluble?) at urine pH.
basic
cysteine, ornithine, arginine and lysine (COAL).
transport membrane protein
renal calculi
cystine
Insoluble
Hartnup’s disease:
This is due to the inability of the renal tubules to absorb ______ with the exception of ___.
Clinical feature include pellagra (rough skin) due to loss of ______ in urine.
all other amino acids
COAL
tryptophan
Amino acid transport disorders
———-
______
______
Cystinuria
Dicarboxylic aminoaciduria
Hartnup disease
