Amines, Amino Acids and Protein Flashcards
_________are compounds in which one or more of the hydrogen atoms of the ammonia molecule have been replaced by hydrocarbon groups.
Amines
____________ are classified as 1, 2 or 3 according to the number of hydrogen atoms that have been replaced
Amines
- the unshared electron pair on the N atom is responsible for most of the chemical properties of amines
- It act as Lewis bases and are nucleophiles
- It also make an aromatic ring strongly activated towards electrophilic aromatic substitution (EAS) reactions
Amines
They are polar compounds, and both 1° and 2° amines form
intermolecular hydrogen bond
Amines
Proteins with only 1 peptide chain. (Tertiary Structure)
Monomeric proteins
Proteins with more than 1 polypeptide chain. (Quaternary Peptides)
Multimeric Proteins
only one kind of polypeptide
Homomultimeric
Several different kinds of polypeptide chains
Heteromultimeric
Each amino acid in a peptide
Moiety or Residue
The residue has a free a-amino group. The 1st amino acid in the sequence
N-terminal residue
The residue has a free carboxyl group.
C-terminal residue
- They are basic compounds
- Small aliphatic amines (< 5C) are water-soluble and their solutions give a basic response (pH>7) when tested with litmus paper
Solubility of Amines in Water
- As the number of C atoms increases, solubility decreases
- Although most amines are not-soluble, amine salts are generally water soluble
Solubility of Amines in Water
- More substituted or the larger the nonpolar group, the less soluble the sample is.
- The more substituted, the more basic
Solubility of Amines in Water
It depends on the side chain
Amino acids
Solubility in 6M HCl is a positive identification test for bases. Amines that are insoluble in pure water will be soluble in acid due to the formation of an ammonium chloride salt.
Solubility of Amines in Aqueous Acid
In solubility of Amines in Water, ________ are readily protonated by strong acids such as HCL and H2SO4.
- _______ react with acids forming positively charge quaternary amines
Amines
Generally used to detect the presence of the free a-amino groups in amino acids, polypeptides and proteins
Ninhydrin Test
Reagent - Ninhydrin Solution
Ninhydrin Test
Positive Result: Appearance of blue to violet colored spot due to the formation of diketohydrindamine (DYDA)
Ninhydrin Test
____________, whether soluble or insoluble in water, react quantitatively with
strong acids to form water-soluble salts.
amines
-__________are the building blocks of proteins.
- Each ___________ has a carboxyl group, an amino group, and a
distinctive side chain (R-group) bonded to the ∝-carbon
Amino acid
there are about ___ different α-amino acids obtained from the hydrolysis of
different proteins and they differ only in the nature of the R groups
20
- absolute configuration
- It does not indicate the direction by which the molecule rotate plane
polarized light
D and L configuration
The _______ and _________in aa undergo internal acid-base
reaction to form an internal salt
amino and carboxyl groups
amino acids can exist as _________ or polar ions:
zwitterions
It formed by condensation reaction of amino acids with the removal of
water
Peptides
- They are complex nitrogenous organic substances involved in all phases of cell metabolism
- They very large and essentially consist of one or more long chains which are coiled and folded in a definite number
Proteins
- Its individual chains are made up of amino acids which are connected by amide linkages or peptide
bonds. - Hydrolysis of proteins yields the component amino
acids
Proteins
It was made up of one or more polypeptides folded in specific conformations
Protein
_____________ is a linear polymer of amino acids.
Polypeptide chain
The sequential order of aa along the chain is a characteristic for a given protein. (N-terminal and C-terminal)
Primary Structure
- refers to the manner in which the aa are arranged in space
- some protein chains are arranged in the form of α-helix or β-pleated
sheet
Secondary Structure
- It refers to the manner in which the protein molecule is folded
- polypeptide chains arranged in long strands or sheets (fibrous)
- polypeptide chains folded into spherical or globular shape (globular)
Tertiary Structure
It describes the organization of subunits in a protein with multiple subunits (oligomeric protein)
Quaternary Structure
- the biological activity of a protein depends on its structure
- destruction of protein’s proper conformation
- disruption of forces that stabilize the 2, 3 and 4 structures
Protein Denaturation
- Results in changes in physical properties (precipitation or coagulation) and loss of biological activity
- It may be caused by the action of heat, light, and chemical agents such as alcohols, strong acids and bases, detergents, and heavy metals such as Hg (II) and Pb (II)
Protein Denaturation
It is used to detect the presence of two or more peptide linkages in proteins and their larger hydrolytic products (proteoses and peptones).
Biuret Test
Reagent: alkaline copper (II) sulfate
Biuret Test
(+) result: formation of violet-colored coordination
complex due to the coordination of cupric ions with
the unshared electron pairs of the peptide
Biuret Test
Sulfur in sulfur-containing proteins and amino acids can be released as
sulfides by the action of strong alkali.
- the sulfides can be precipitated by lead acetate
Reaction with Lead Acetate
Reagent: NaOH/Pb(CH3 COO)
Reaction with Lead Acetate
(+) result: Formation of black precipitate
Reaction with Lead Acetate
____________ is associated with the alteration of the secondary and tertiary structures of biological proteins which results in changes in physical properties and loss of biological activity.
Protein Denaturation
- May be caused by the action of heat, light, alcohols,
strong acids and bases, and other denaturing agents.
Protein Denaturation
(+) result: appearance of precipitate or coagulated product
Protein Denaturation
Treatment of amine with benzesulfonyl in aqueous sodium hydroxide and then acidified with HCL
Hinsberg Test
Addition of Hinsberg Solution in primary amines will results to
clear solution (+)
Addition of Hinsberg Solution in secondary amines will results to
suspension or oil formation (-)
Addition of Hinsberg Solution in tertiary amines will results to
suspension or oil formation (-)
Addition of HCL to 1 amines will results to
appearance of precipitate
Addition of HCL to 2 amines will results to
suspension or oil formation
Addition of HCL to 3 amines will results to
clear solution
