Protein Matebolis Flashcards by Iseoluwa Ojo

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.

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Essential must get in diet Non-essential mammals synthesize

__* (children only)
____* (children only)
list the rest

Arg
His

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•Dietary proteins (can or cannot?) be absorbed directly from the intestine.

Cannot

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To be absorbed, dietary protein must be digested into small simple molecules (______) which are easily absorbed into the small intestine.

amino acids

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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.

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Steps in Protein digestion

•Protein digestion starts in the _______.

stomach

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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.

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Steps in Protein digestion contd.

•The pancreatic juice produced by the pancreas contains inactive protein digesting enzymes namely ______,______,_____

trypsinogen, chymotrypsinogen and procarboxy-peptidase.

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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

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Steps in Protein digestion contd.

•Chymotrypsinogen is activated by ____ to __-chymotrypsin by removing a short peptide from it

trypsin; b

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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

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Steps in Protein digestion contd

Procarboxy-peptidase is activated by ____ to carboxypeptidase.

The active enzyme hydrolyses ___ peptide linkage with _______ group.

trypsin

end; free carboxylic

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Steps in Protein digestion contd

Succus entericus produced by ______ cells contains _________ and _____

intestinal mucosa

aminopeptidase and dipeptidase.

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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

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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

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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

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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.

Soluble; paracasein; calcium

Insoluble

calcium paracaseinate

pepsin

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Gelatinase
It is an enzyme that _______ ———

The end products of protein digestion in the stomach are ————,———,——-

liquefies gelatin.

proteases, peptones and large polypeptides.

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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

enterokinase

autoactivation

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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

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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.

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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

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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

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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.

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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. 1. _______________ system 2. __________ transport system

Carrier proteins transport Glutathione

Pathways for amino acid degradation In animals, amino acids undergo _________ in three different metabolic circumstances: 1. During the normal synthesis and degradation of cellular proteins, some amino acids that are released from protein breakdown and are _____________ undergo oxidative degradation. 2. When a diet is rich in protein and the ingested amino acids __________, the surplus is catabolized 3. 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 1. 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 2. Decarboxylation: ____ of _____ 3. Racemization: interconversion of ____ and ___ forms. 4. _____ and ———-e deamination 5. ____lization 6. Elimination and replacement reaction ___-carbon of amino acid 7. 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