Amino Acids and Aminoacidopathies and Detection Methods I and II
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297 Terms
What are amino acids?
the basic structural units of all proteins and peptides.
What is the general formula for amino acids?
The general formula for amino acids is RCH(NH2)COOH.
What groups make up an amino acid structure?
An amino acid consists of an amino group (NH2), a carbonyl group (COOH), a hydrogen (H), and a chemical group or side chain (R).
What does the "R" represent in an amino acid?
a chemical group or side chain that gives each amino acid its distinctive properties.
How does the "R" group affect amino acids?
It determines the chemical and structural diversity of amino acids, affecting properties like charge, polarity, hydrophilicity, hydrophobicity, and 3-D shape.
What determines a protein’s 3-dimensional structure and function?
Amino acids determine a protein's 3-dimensional structure and function through their composition and arrangement.
How are proteins in the diet processed in the body?
Proteins in the diet are digested into individual amino acids.
What are the two main pathways that amino acids participate in for energy production?
Amino acids can be metabolized into either glucogenic (generating glucose precursors like pyruvate) or ketogenic (producing ketones or acetyl-CoA) pathways.
What is the role of amino acids in energy metabolism?
Amino acids provide energy by generating glucose precursors (glucogenic) or ketones (ketogenic) and can be used in the Krebs cycle for energy production.
What is the isoelectric point (pI) of an amino acid?
The isoelectric point (pI) is the pH at which an amino acid has a balanced charge, making it neutral.
What is a zwitterion in amino acids?
A neutral molecule that has both positive and negative electrical charges, which can switch based on the pH.
What are some purposes amino acids are used for in the body?
to synthesize non-protein nitrogen compounds (e.g., urea) and for energy metabolism.
What is the role of amino acids in urea synthesis?
Amino acids, like arginine, are involved in synthesizing urea, which helps remove ammonia from the body.
What does glucogenic metabolism of amino acids involve?
Glucogenic amino acids generate precursors of glucose, such as pyruvate.
What does ketogenic metabolism of amino acids involve?
Ketogenic amino acids produce ketones for energy or are converted to acetyl-CoA.
What is the role of amino acids in the ketogenic diet?
In a ketogenic diet (low-carb diet), amino acids are metabolized to produce ketones or acetyl-CoA for energy.
Can amino acids be metabolized in both glucogenic and ketogenic pathways?
Yes, some amino acids can enter either the glucogenic or ketogenic pathway, depending on the need for glucose or ketones.
How do amino acids participate in metabolism?
Amino acids participate in the metabolism of proteins, carbohydrates, and lipids (the three macronutrients)
How do amino acids help in energy production?
Amino acids contribute to energy production by participating in the Krebs cycle, providing energy for cells to grow and divide.
What is special about the α-carbon of amino acids?
All amino acids (except glycine) have four different groups attached to the α-carbon.
What is unique about glycine compared to other amino acids?
Glycine has two hydrogen atoms attached to the α-carbon, making it the only amino acid that is not optically active (achiral).
What does it mean when an amino acid is optically active?
Optically active amino acids are stereoisomers (chiral), meaning they have non-superimposable mirror images.
Why is glycine not considered optically active?
because it is achiral, meaning it has two hydrogen atoms attached to its α-carbon.
What configuration do all naturally-occurring amino acids in proteins have?
All naturally-occurring amino acids found in proteins have the “L” configuration.
How can you determine whether an amino acid is D Dextrorotatory L: Levorotatory
To determine D or L isomerism, follow the "CORN" rule, which involves observing the arrangement of groups around the α-carbon atom.
What is the CORN rule for determining D/L isomerism?
The CORN rule involves sighting from the hydrogen atom. If the groups around the α-carbon are arranged clockwise, it's the L-form; if counter-clockwise, it's the D-form.
What are essential amino acids?
those that humans cannot synthesize and must obtain through diet.
What are some examples of essential amino acids?
Histidine
Isoleucine
Leucine
Threonine
Lysine
Methionine
Phenylalanine
Tryptophan
Valine
How can you remember the essential amino acids?
"Help In Learning These Little Molecules Proves Truly Valuable."
What are conditionally non-essential amino acids?
Arginine
Cysteine
Glutamine
Glycine
Proline
Tyrosine
What are examples of non-essential amino acids?
Alanine
Asparagine
Aspartate
Glutamate
Serine
How are amino acids organized when they share the same starting letter
They are ordered by size, with the smallest one appearing first
What are the characteristics of nonpolar aliphatic amino acids?
Hydrophobic
Symmetrical electron distribution in their R group
Do not have OH,SH, or amine groups
Why are nonpolar amino acids hydrophobic?
because they have a hydrocarbon-based R group with symmetrical charge, making them unfavorable to interact with water molecules.
Where are nonpolar amino acids typically located in a protein?
are often located in the core of the protein, buried in the hydrophobic core and shielded from aqueous surroundings by the rest of the protein.
What is the main feature of the R group in nonpolar amino acids?
It consists mainly of hydrocarbons, with no OH, SH, or amine groups, leading to a balanced or symmetrical charge.
Why can't nonpolar amino acids participate in hydrogen bonding?
because their R groups have different electronegativity and asymmetric charge, preventing them from forming hydrogen bonds.
How do nonpolar amino acids behave at physiological pH?
At physiological pH, nonpolar amino acids have uncharged functional groups and do not participate in hydrogen bonding.
What is the primary reason nonpolar amino acids are not soluble in water?
do not interact well with water due to their hydrophobic nature, caused by the symmetrical electron distribution in their R group.
What is unique about glycine?
It is the simplest and smallest amino acid and is the only one that is not optically active because it has two hydrogen atoms attached to its α-carbon.
What is glycine a derivative of?
acetic acid via amination, making it amino acetic acid.
What role does glycine play in the body?
the biosynthesis of purines (adenine and guanine) and porphyrins (heme) in hemoglobin. It also helps improve wrinkles in conjunction with leucine and proline (anti-aging) and is important for collagen formation.
What is the side chain of alanine (Ala)?
It has a methyl group as its side chain.
What enzyme is alanine a substrate for?
a substrate for alanine aminotransferase (ALT), a liver enzyme.
What does alanine aminotransferase (ALT) do?
ALT converts alanine to pyruvate and vice versa.
What was ALT previously called?
serum glutamic pyruvic transaminase (sGPT).
Is alanine a glucogenic amino acid?
Yes, alanine is a glucogenic amino acid.
How are alanine and pyruvate related?
They are interchangeable through a transamination reaction, where the amino group from alanine is transferred to a keto group (C=O), forming pyruvate.
What type of reaction is mediated by alanine aminotransferase (ALT)?
a transamination reaction, where an amino group is transferred from an amino acid to a keto group.
Why is alanine important for glucose metabolism?
because it can be converted to pyruvate, which is a key intermediate in glucose production.
How does valine (Val) differ from threonine (Thr)?
by the replacement of the hydroxyl group (OH) with a methyl group.
What functional group does valine contain in its side chain?
a methyl group in its side chain.
What category of amino acids does valine belong to?
one of the three branched-chain amino acids (BCAAs).
Is valine ketogenic or glucogenic?
ketogenic
How does valine produce energy?
It is broken down into acetyl-CoA, which enters the citric acid cycle for energy production.
Why is valine important for the body?
essential for muscle metabolism and energy production.
How is leucine (Leu) similar to valine (Val)?
Leucine is similar to valine but has an extra methyl group attached to the β-carbon in its side chain.
What category of amino acids does leucine belong to?
one of the three branched-chain amino acids (BCAAs).
Is leucine ketogenic or glucogenic?
ketogenic.
How is leucine used in the body for energy?
is used as a source of energy via ketones and is broken down to produce energy.
What role does leucine play in muscle recovery?
helps reduce muscle protein breakdown and aids in muscle recovery.
How does leucine contribute to skin health?
helps with skin maintenance and acts as an anti-aging agent.
What is Maple Syrup Urine Disease (MSUD)?
A disease caused by faulty metabolism of leucine due to a deficiency in branched-chain α-ketoacid dehydrogenase complex (BCKDC), leading to a buildup of branched-chain amino acids (BCAAs) like leucine, isoleucine, and valine.
What happens in the body during MSUD?
the accumulation of BCAAs and their toxic byproducts (ketoacids) in the blood and urine occurs, causing health issues.
How is isoleucine (Ile) similar to leucine (Leu)?
Isoleucine is similar to leucine, but the orientation of the atoms in the side chain is different.
How does isoleucine differ from leucine in terms of structure?
Isoleucine has a CH2 group at the γ-carbon
What category of amino acids does isoleucine belong to?
one of the three branched-chain amino acids (BCAAs).
Is isoleucine involved in covalent chemistry in enzyme active centers?
No, isoleucine is not involved in covalent chemistry in enzyme active centers because its side chain is not reactive.
Is isoleucine ketogenic or glucogenic?
partly ketogenic.
How does isoleucine contribute to muscle recovery?
promotes muscle recovery after physical exercise.
Why is isoleucine important for hemoglobin formation?
tissue oxygenation
How is proline (Pro) unique compared to other amino acids?
the only amino acid with its side chain bonded to both the α-carbon and the amino group.
Which part of proline is not involved in its ring formation?
The COO- group
What type of structure does proline have?
The only cyclic amino acid, containing an α-imino group that forms an imino ring
Is proline considered an imino acid or an amino acid?
an imino acid rather than a regular amino acid.
What role does proline play in connective tissues?
an important constituent of connective tissue proteins, such as collagen and elastin, which are essential for heart muscle structure.
How does proline benefit the skin?
improves skin texture and aids in collagen formation, which helps to reduce the loss of collagen during aging.
Why is collagen important, and how does proline contribute?
Collagen is the most abundant protein in the body and plays a crucial role in maintaining skin elasticity and strength. Proline helps in its formation and helps prevent collagen loss during aging.
What structure does phenylalanine (Phe) contain in its side chain?
A phenyl ring attached to a methylene group.
How is phenylalanine related to alanine?
It is a derivative of alanine, with a phenyl substituent on the β-carbon.
Why is phenylalanine considered a hydrophobic amino acid?
Due to the phenyl ring in its side chain, phenylalanine is hydrophobic.
What is phenylalanine a precursor to?
tyrosine.
What condition results from the faulty metabolism of phenylalanine?
Phenylketonuria (PKU), a condition where phenylalanine builds up in the body.
What causes Phenylketonuria (PKU)?
PKU is caused by a defect in the enzyme that metabolizes phenylalanine, specifically phenyl hydroxylase deficiency.
What happens to the blood levels in individuals with PKU?
In PKU, there is a lack of tyrosine in the blood, which can lead to conditions such as albinism.
How does tyrosine (Tyr) differ from phenylalanine (Phe)?
Tyrosine is phenylalanine with an additional hydroxyl group (-OH) at the end of the phenyl ring.
Why is tyrosine more hydrophilic than phenylalanine?
The hydroxyl group (-OH) makes tyrosine less hydrophobic and more hydrophilic and polar compared to phenylalanine.
What is the purpose of Folin’s reagent in the Lowry method?
It is used for tyrosine determination and total protein determination in the Lowry method. It contains phosphomolybdate and phosphotungstate, which react with tyrosine and other protein components to produce a measurable color change.
What important neurotransmitters are synthesized from tyrosine?
dopamine, norepinephrine, and epinephrine (catecholamines).
What other important molecules are derived from tyrosine?
melanin (skin pigment) and thyroid hormones.
What structure is present in tryptophan (Trp)?
an indole ring, which is a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring.
Why is tryptophan considered highly hydrophobic
Due to its indole ring, tryptophan is highly hydrophobic.
What important molecules are synthesized from tryptophan?
serotonin (a neurotransmitter)
melatonin (a neurohormone and sleep hormone),
niacin (Vitamin B3).
What clinical condition involves tryptophan metabolites?
Tryptophan metabolites, such as serotonin, are found in carcinoid disease or syndrome.
What causes carcinoid syndrome?
caused by the endogenous secretion of serotonin and kallikrein (a serine protease) in the digestive tract, and it is a type of neuroendocrine tumor that most often occurs in the gastrointestinal tract or lungs.
What is the role of aromatic amino acids in laboratory applications?
They absorb UV light and contribute to the absorbance spectra of proteins, which can be used for protein concentration estimation.
At which wavelength is protein concentration often measured using aromatic amino acids?
280 nm.
What is a key feature of aromatic amino acids?
contain an aromatic ring as part of their side chains.
Are all aromatic amino acids hydrophobic?
All aromatic amino acids are highly hydrophobic except for tyrosine, which is less hydrophobic due to its hydroxyl group (-OH).
Why is tyrosine less hydrophobic than other aromatic amino acids?
Because the hydroxyl group (-OH) on its phenyl ring increases its hydrophilicity.