Chapter 4 Proteins And Amino Acids Flashcards
Most of the aminoacids are?
Alpha- amino acids
Most abundant organic molecules of living system?
Proteins
Proteins constitute about ________% of dry weight of a cell?
50
Proteios means?
Holding the first place
Entire study of galaxy of proteins is given the term?
Proteiomics
Function of proteins may be grouped as?
1.Static (structural)
2.Dynamic
What are the structural proteins?
That perform brick and mortar functions.
Structure and strength
E.g:
Collagen
Elastin
- both in bone matrix and vascular tissues
a-keratin - in epidermal tissues
What are dynamic proteins?
Act as enzymes, harmones, immunoglobins, storage proteins etc
- regarded as working horses of cell
Content of nitrogen in protein?
16%
Estimation of nitrogen in laboratory is mostly done by?
Kjeldahl’s Method
Proteins are polymers of?
L-a-aminoacids
Proteins are hydrolysed by?
Concentrated HCl
How many amino acids occur in nature?
300
How many amino acids are known as standard amino acids?
20
1.Trick to remember aliphatic amino acids?
- Trick to remember aromatic aminoacids?
Aliphatic amino acids;
(Glaciers in Alaska Valiantly Locate Isolated Prowlers)
Glycine (only one containing non-chiral carbon)
Alanaine
Valine
Leusine
Isoleusine
Proline (only one containing ring but not aromatic)
- (The Aroma of Fine pine & Yellow Timber are Worth the Tryp)
Aroma—aromatic:
•Phenylalanine (F)
•Tyrosine (Y) (also contains OH group)
•Tryptophan (W)
(2 aromatic rings, 1st—5 membered, 2nd—6 membered)
- Trick to remember amino acids containing hydroxyl group?
- Trick for basic amino acids?
- (Alcohol is a Serious Threat)
Alcohol—alcoholic group (-OH)
•Serine
•Threonine
- (Basically,
His
Lost Kid
Always Returned)
Basically—-basic amino acids
•Histidine (H)
•Lysine (K)
•Arginine (R)
Trick for acidic amino acids & their amide?.
What are the sulfur containing amino acids?
(As he Digested the Glue his stomach became acidic)
Aspartic acid (D)
(Amide—-Asparagine (N))
Glutamic acid (E)
(Amide—-Glutamine (Q))
- Methionine
Cysteine
Cystine
Importance of amino acids regarding charges & polar/non-polar nature?
-
charged
Acid & basic amino acids -
Non-polar
•All aliphatic
•2 aromatic
(phenylalanin & tryptophan)
• methionine -
Polar
•All alcohols & amide
•Aromatic —-Tyrosine (bcz has OH group)
•Cysteine
1.All amino acids show optical isomers except?
- What type of amino acids are proteins composed of?
- Name the branched chain amino acids?
- Cystine is formed by?
- What are the 2 amino acids incorporated during protein synthesis? With special groups??
1.Glycine (no chiral/asymmetrical carbon)
- L-a-aminoacids
- There are 3 aliphatic amino acids with branched chains:
Valine
Leucine
Isoleucine - Condensation of 2 molecules of cysteine
- 2 sulfur containing;
Methionine (thioether group)
Cysteine (sulfhydryl group)
- What are the dicarboxylic monoamino acids?
- Groups in arginine & histidine? What kind of aminoacids are these?
- What is an imino acid? Name it?
- Name heterocyclic amino acids?
- Aspartic acid & glutamic acid
- Arginine—-guanido
Histidine—-imidazole
—dibasic monocarboxylic aminoacids - Containing imino group (=NH) instead of amino (-NH2)
Proline (pyrridole ring)—is an a-imino acid - Histidine
Tryptophan
Proline
- What are the polar amino acids with positive R group?
- What are the polar amino acids with negative R group?
- Polar amino acid but with no charge?
- Basic amino acids:
Histidine
Lysine
Arginine - Acidic amino acids:(dicarboxylic):
Aspartic acid
Glutamic acid - •Glycine
Alcoholic
•Serine
•Threonine
Sulfur containing
•Cysteine
Amide
•Glutamine
•Asparagine
Aromatic
•Tyrosine (-OH group)
- What are essential amino acids? Which of these are semi essential?
Which can’t be synthesized in the body
(Argentina.Valley. HILL M.P Threat.Tryp)
Arginine
Valine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylanaline
Threonine
Tryptophan
Semi essential
Can be synthesized by adults but not by growing children;
(Ah)
Arginine
Histidine
- What is the fate if amino acids?
- Either as precursor of
•Glucose—-(glycogenic aminoacids)
(AA)
Alanine
Aspartate
Glycine
Methionine.
•Fat—-(ketogenic aminoacids)
(LL)
Leucine
Lysine
•Glycogenic & ketogenic aminoacids
4 amino acids:
(3 aromatic and 1 aliphatic)
Tryptophan
Tyrosine
Phenylalanine
Isoleucine
- What is the 21st amino acid? It is translated by which stop codon?
Incorporated directly on protein by?
It is found in?
What is the difference in its structure compared to cysteine? - What is the 22nd amino acid? It is translated by which stop codon?
-
Selenocysteine
–By UGA
–By serine on tRNA
– at the active sites of enzymes (selenoproteins) e.g
Glutathione peroxidase
5’-diodinase
—-selenium in place of Sulfur atom of cysteine -
Pyrrolysine
By UAG
1.What is chinese restaurant synrome?
- Name amino acids that are
Sweet
Tasteless
Bitter
Chinese restaurant syndrome is a term used to describe a collection of symptoms, such as headaches, flushing, and sweating, that some people may experience after consuming foods containing monosodium glutamate (MSG). (Ajinomoto(brand name) –flavour enchancer)
It was initially associated with Chinese cuisine, hence the name, but it can occur after consuming foods from various cuisines that contain MSG.
2.
Sweet— Glycine, Alanine, Valine
Tasteless—leucine
Bitter—Arginine, Isoleucine
- What are ampholytes?
- Nature of amino acids in different pH?
- What is isoelectric pH?
1.Ampholytes are substances that can act as both acids and bases.
E.g aminoacids
They have the ability to donate (-COOH) (acidic) or
accept protons (-NH2) (basic) depending on the pH of the environment.
It’s like they can play both roles, kind of like being versatile!
-
acidic pH(low pH)
Amino acid—-+vely charged cation
alkaline pH(high pH)
Amino acid—- -vely charged anion
Neutral PH
As zwitter ion
E.g leucine (pH=6.0) - The isoelectric pH, also known as the pI (isoelectric point), is the pH at which a molecule or substance has no net electrical charge.
It exists as zwitter ion or dipolar ion
It’s like finding the perfect balance point where the molecule is neither positive nor negative.
- What happens on decarboxylation of amino acids?
- Name biologically imp amines from corresponding amino acids?
- Amides are formed by reactions of?
- Which test is used for detection of amino acids & proteins?
- Amines are formed
2.
Histidine—-histamine
Tyrosine—-tyramine
Glutamate—-y-Amino Butyric Acid (GABA)
- Carboxyl group of dicarboxylic Aminoacids + NH3
-
Ninhydrin test
Amino acids + Ninhydrin—–purple/blue/pink complex
But
Proline & hydroxyproline—-yellow colour
- Collagen contains amino acid derivatives?
- Which amino acid derivative is involved in blood clotting?
- Amino acid derivatives found in histones?
1.
4-Hydroxyproline
5-Hydroxylysine
- Y-Carboxyglutamic acid found in plasma proteins
- Methylated
Phosphorylated
Acetylated amino acids
- D-amino acids are found in antibiotics?
- D-amino acids are found in brain tissue?
3.D-amino acids are found in bacterial cell wall?
- •Actinomycin - D
•Valinomycin - D
•Gramicidin - S - •D- Serine
•D- Aspartate - •D-Glutamic Acid
•D-Alanine
1.Name 3 amino acids used as drugs?
- Which amino acid drug is used for treatment of cystic fibrosis?
- Which drug is used for the treatment of wilson’s disease?
- Which amino acid drug is used as an anticonvulsant?
- •D-pencillamine
•N-Acetylcysteine
•Gabapentin -
N-Acetylcysteine
As it acts as antioxidant
( by thinning the mucus in the airways, making it easier to cough up.) -
D-penicillamine (D-dimethylglycine)
Chelation of copper
D-penicillamine treats Wilson disease by binding to copper and forming a complex that can be excreted in urine. This helps reduce copper levels in the body. -
Gabapentin (y-aminobutyrate)
Linked to cyclohexane
(by binding to certain receptors in the brain that help reduce abnormal electrical activity and prevent seizures.)
- What is lathyrism?
- What amino acids are responsible for it?
- Which amino acids in it cause ammonia toxicity?
- Which amino acids is responsible for parkinson’s dimentia?
1.Lathyrism is a condition caused by the consumption of a legume called Lathyrus sativus (kesari dal), which contains a neurotoxin. It can lead to paralysis of the lower limbs.
-
L-Homoarginine &
B-N- OxalylDiAminoPropionic acid (ODAP) of lathyrus -
a,y-diaminobutyric acid
(Analogue of ornithine)
—-bcz it disrupts urea cycle -
L-B-Methylaminoalanine
Of Cycad seeds
- Peptide bonds is charged or uncharged? Peptides may be also regarded as?
- In polypeptide chains 2 adjacent a-carbons are placed?
- Which structure of protein is primarily responsible for its function?
- Which enzyme causes complete hydrolysis of proteins?
- Peptide bond—- uncharged
But peptides —- charged (due to terminal carboxyl & amino group)
Thus peptides—–polyelectrolytes - 0.36nm apart
- Primary structure
- Prolase (a mixture of non-specific proteolytic enzyme)
- How amino acids can be separated after protein hydrolysis?
- By chromatography
(Amino acids can be separated by chromatography based on their different properties, such as size, charge, and affinity for the stationary phase. It’s like giving each amino acid its own unique pathway to travel, allowing them to be separated and identified. )
- The non-covalent bonds between proteins are broken by?
- Disulfide linkages are cleaved by?
- Number of polypeptide chains can be identified by treatment of protein with?
- Enzymatic cleavage is done by?
- Chemical cleavage by?
-
Urea or guanidine hydrochloride
(Converts proteins —- polypeptides) - Performic acid
- Dansyl chloride
-
Trypsin
(Carbonyl side of peptide linkage containing lysine & arginine) -
Cyanogen bromide (CNBr)
(Carbonyl side of peptide linkage containing methionine)
- Determination of amino acids by?
- Sequenator uses which principle?
-
Sangers reagent
(1-fluoro 2,4-dinitrobenzene)
Edman’s reagent
(Phenyl isothyiocyanate)
Then amino acid by chromatography
- An automated machine for amino acid sequence
—Edman’s principle
(PTH amino acid is liberated)
- The a-helix is stabilized by?
- Each turn of a-helix has how many:
Amino acids?
Travels of distance of?
Spacing of each amino acid? - Which a-helix is more stable?
- Extensive Hydrogen bonding between H-atom of peptide N & O-atom of peptide C
2.
Amino acids—–3.6
Travels of distance of—0.54nm
Spacing of each amino acid—0.15nm
- Right handed a-helix is more stable than left
- In globular proteins, the core structure is formed by?
- What are supersecondary structure of proteins?
Stabilized by?
Also called?
- B-sheets
- Intermediates between secondary & tertiary structures
-combination of a-helices & B-structures
—stabilized by;
•H-bonding
•Salt bridges
•Hydrophobic interactions
—also called — mortif
- Bonds in tertiary structures of proteins?
- What is domain?
- A polypeptide with 200 amino acid contains how many domains?
- What are oligomeric proteins?
Examples? - Bonds in quaternary structure?
- •Hydrogen bonds
•Disulfide bonds
•Ionic interactions
•Hydrophobic interactions
•Van der waals forces - Term used to represent the basic unit of tertiary protein structure
- 2 or more domains
- Having quaternary structure (2 or more polypeptides)
E.g
Hemoglobin
Aspartate transcarbamoylase
Lactate dehydrogenase - •Hydrogen bond
•Hydrophobic interaction
•Ionic interaction
- Chemically glutathione is?
- How is it essential for protein function?
- What is it’s significance in eryhthrocyte?
- Involved in amino acids transports in the intestine & kidney tubules by?
- Peroxidases & free radicals are scavenged by?
-
y-glutamyl-cysteinyl-glycine
Is a tripeptide composed of 3 amino acids - Prevents oxidation of sulfhydryl groups of proteins to disulfide groups
— also with glutathione reductase— formation of correct disulfide bonds -
Gutathione (reduced):
•Maintains RBC membrane structure
•Protects Hb from oxidation by H2O2 - y-glutamyl cycle/Meister cycle
-
Glutathione peroxidase
(A selenium containing enzyme)
- Name different peptides with different numbers of aminoacids (peptides)
Dipeptide (2 amino acids)
•Aspartame
Tripeptides (3 amino acids)
•Thyrotrophin releasing hormone
•Glutathione
Pentapeptide
•Methionine enkephalin
Octapeptide
•Angiotensin II
Nonapeptides
•Oxytocin
•Vasopressin (ADH)
•Bradykinin
Decapeptides
•Angiotensin I
•Kallidin
- What are pseudopeptides?
- Which peptide is found in brain? Its function?
- What is the function of bradykinin and kallidin?
- Aspartame is _____ times sweeter than?
Used as?
Produced by combination of?
- Duplicate peptides produced by pharmaceutical industries to the efficiency of drugs
E.g
B-peptides
Y-peptides
Oligoglycines
Peptide nucleic acid (PNA)
DNA cleaving pseudopeptides -
Methionine enkephalin (pentapeptide)
—opiate like function
—inhibits sense of pain - Vasodilators
- produced from plasma proteins by snake venom enzymes -
200 times than sucrose
—artificial sweetener
—aspartic acid & phenylalanine
What are covalent & non covalent bonds in protein structures?
-
2 covalent
Peptide
Disulfide
4 non covalent
Hydrogen bonds
Hydrophobic bonds
Electrostatic bonds
Van der waals forces
