AMINO ACIDS & PEPTIDES Flashcards
What is histidine?
Histidine is a precursor of histamine which is a vital compound involved in immune responses, allergic reactions and gastric acid secretion.
What are amino acids
Amino acids are chemical compounds that contain an alpha carbon atom, a carboxylate group, an amino group and an hydrogen atom.
Describe the ionization of amino acids in water
When amino acids react with water it ionizes as the carboxylate group loses a H+ ion which makes it negatively charged and the amino group gains the H+ making it positively charged
Classifications of Amino Acidsl
Classified Based On Nutritional.
Classified based on R group
Classify Amino acids based on Nutrition
Essential Amino acids.
Non-essential Amino acids
Classification Based on R group
Non polar aliphatic R group
Polar Uncharged R group
Aromatic R group
Positively Charged R group
Negatively Charged group
What are Non Polar Aliphatic R Groups
Examples of Non Polar Aliphatic R Group
The hydrocarbon R group in this class of amino acid is hydrophobic and non polar.
Glycine, Alanine, Valine, Leucine, Isoleucine and Methionine
What are Polar Uncharged R groups with examples
The R group of these amino acids are more soluble in water or hydrophilic than those of non polar amino acids this is because their functional group is capable of forming hydrogen bond with water
Examples- Serine, Threonine, Cysteine, Asparagine, Glutamine, Proline
What are Aromatic R Group and examples
Their Aromatic side chains are relatively non polar and they participate in hydrophobic interactions.
Examples- phenylalanine, tryptophan, tyrosine
What are positively charged R Group with examples
These are amino acids in which the R group has a net positive charge at PH 7.0
examples- Histidine, arginine and Lysine
What are Negatively Charged R groups
Examples
These are R groups with net negative charge at PH 7.0 with a second carboxyl group
examples- Aspartate and Glutamate
What are Essential Amino acids
Examples,??
Essential Amino acids are amino acids that cannot be produced in sufficient quantity by the body and need to be supplied in diet.
Players - PHENYLALANINE
Love - LEUCINE
Tackling - THREONINE
Lionel - LYSINE
Messi - METHIONINE
Haaland and - HISTIDINE
Isak- ISOLEUCINE
on
TV- TRYPTOPHAN
VALINE.
What are Non essential amino acids
Examples
These are amino acids that the body can produce in sufficient quantity and it need not to to be supplied in daily diet
Examples- Aspartate, Glutamate, Asparagine, Glutamine, Cysteine, Proline, Glycine, Alanine, Serine, Arginine, Tyrosine
What are the 4 special Amino acids
Cysteine, Selenocysteine, Proline and Glycine
Why is Glycine a special Amino acid
Glycine is a special Amino acid because it contains hydrogen as it side chain rather than a carbon as is the case of all other amino acids
Why is Selenocysteine a special amino acid
It is similar in structure to cysteine, the only difference is that it has selenium instead of sulfur in it’s side chain
Why is Cysteine a special amino acid
Cysteine is a special amino acid because It has an active sulfhydryl (thiol) group that forms disulfide bridges(s-s) between regions of the protein chain
Why is Proline a special amino acid
Proline is unique among standard amino acids because it does not have both free alpha amino group and free alpha carboxyl group instead its side chain forms a cyclic structure as the nitrogen atom of Proline is linked to two carbon atoms.
List two other processes amino acids participate in
Neurotransmitter transport and biosynthesis
Properties of Amino Acid
- Soluble in water
- Have either high melting point or decompose upon heating (they act more like inorganic materials than organic compounds)
- R groups vary in structure, size and electric charges which influences the solubility of amino acid in water.
What is pyrrolysine
Pyrrolysine is a lysine in which a pyrroline ring is linked to the end of a lysine side chain. It was discovered in Archaea and bacteria. Pyrrolysine is the 22nd genetically coded amino acid and it plays a unique role in the keys step in the growth of methanogens on mono-, di-, and tri- methylamines by activating the methyl groups of these substrates for transfer to the corrinoid cofactor
more properties of amino acids
- Amino acids form internal salts called zwitterions.
- All Amino acids except Glycine have handedness (chirality).
- In zwitterions of amino acids they have uncharged side chains because the positive and negative charges cancel one another.
- Amino acids in which the positive charge and negative charge are balanced is at it’s isoelectric point.
- The pH at which this balancing occurs is the Isoelectric pH.
- Amino acids are least soluble at it’s isoelectric pH.
- Increases solubility at lower PH as well as higher pH.
- Amino acid links to form peptides
What are peptides
Peptides are compounds in which an amide bond links the amino group of an alpha amino acid and the carboxyl group of another alpha amino acid. An amide bond is often referred to as a peptide bond.
Explain the formation of a peptide bond
