AA PeptProt.ppt Flashcards
What are amines?
Amines are organic chemistry relatives of ammonia
How are the amines structure compared to ammonia?
Amine´s structure resembles ammonia molecules in which alkyl groups take the place of one, two, or all three hydrogen atoms
Primary amines
amines with one alkyl or phenyl group
Secondary amines
amines with two alkyl or phenyl group
Tertiary amines
amines with three alkyl or phenyl group
Amines have similar properties to the properties of …….
ammonia, but modified by the presence of alkyl or phenyl groups
The lone pair electrons are responsible for ammonia being:
- very soluble in water
- a base
- a ligand
- a nucelophile
*these properties are found in amines too
Can ammonia and amines form hydrogen bonds?
yes
The smaller the alkyl groups of the amines are…….
the more soluble it is.
The presence of hydroxide ions makes the solution …….
alkaline
Like ammonia, amines also react with …….
acids. Their reaction with amines is complete and the solution therefore looses its strong amine smell.
Why does ammonia attack electrophiles such as halogenoalkalines?
Ammonia can act as a nucleophile, with the lone pair of electrons on the N atom attacking electrophiles such as halogenoalkalines
How does amines form secondary and tertiary amines?
Amines do substitution reactions with halogenoalkalines. That is because amines like ammonia behave as nucelophiles, because they have a lone pair of N atom, just the same as ammonia
What are amino acids derivatives of?
AA are teh derivatives of carboxylic acid, in which at least a hydrogen atom linked to the side chain is replaced by amine group, NH2
Alpha amino acid
In the alpha amino acid, the α-carbon is a chiral carbon atom, with the exception of glycine
Which forms can the α-amino acids have?
the α-amino acids can exist in either of two optical isomers, called L or D amino acids, which are mirror images of each other
Where can we find L-amino acids?
L-amino acids represent all of the amino acids found in proteins in animals
Where are D-amino acids found?
D-amino acids are found in some proteins of bacteria and lower organisms
An AA has both ……
a basic amine group and an acidic carboxylic group
Zwitterion
A zwitterion is a compound with no overall electrical charge, but which contains separate parts which are positively and negatively charged.
How can you get a zwitterion?
if you dissolve the amino acid in water
Isoelectric point
The value of pH when the amino acid no longer has a net positive or negative charge is called isoelectric point of given amino acid and varies from amino acid to amino acid. The number of protonated ammonia groups (positive charges) and deprotonated carboxylate groups (negative charges) are equal at this point.
Branched-chained amino acid
The phrase “branched-chained amino acid” refers to the amino acids having alphipatic side chains that are non-linear
Which amino acids are branched-chained amino acid?
Leucine, isoleucine, and valine
Which amino acid is an imino acid?
Proline
Why is proline an imino acid?
because it lacks a primary amino group. It may also be called an “N-alkylated alpha-amino acid”
Amino acids can exist as zwitterions in ……….
solids and in polar solutions such as water, but not in the gas phase
How is the solubility for the zwitterions?
Zwitterion have minimal solubility at their isoelectric point and an amino acid can be isolated by precipitating it from water by adjusting the pH to its particular isoelectric point.
AA are precusors fror synthesis of:
- hormones
- biological dyes
- some coenzymes
- neurotransmitters
Hormones:
- adrenaline
- thyroxine
- histamine
- dopamine
Biological dyes:
- melanin
- chemu
What are the fragments of amino acids used for?
they are used for the synthesis of glucose, ketones, or there are oxidized to carbon dioxide and water
peptide bond =
amide bond
What is released during the formation of a peptide bond?
water
What type of reaction is the peptide bond formation?
dehydration synthesis reaction (condensation reaction)
condensation reaction =
dehydration synthesis reaction
What is a oligopeptide?
Oligopeptide (simple peptide) is a single linear chain of amino acids rests (di-, tri, tetra…….octa-, decapeptide, and so on)
What are cyclic peptides?
Cyclic peptides (or cyclic proteins) are polypeptide chains whose amino and carboxyl termini are themselves linked together with a peptide bond that forms a circular chain
What characterize peptide isomers?
Peptide isomers are characterized by an identical formula, but their physical and chemical properties are different
What is a peptide?
Peptide is a molecule consisting of 100 amino acids
How many amino acid residues does a protein have?
The protein chain falls from 100 to 1000 amino acid residues
Hydroxyproline:
formed by hydroxylation of proline (present in collagen and elastin)
Hydroxylysine:
formed by hydroxylation of lysine (found in collagen)
Carboxyglutate:
formed by carboxylation of glutamate (found in plasma protein)
What determines the primary structure of AA?
it is determined genetically
Enzymes digesting proteins:
- trypsine
- chymotrypsine
What are glycoproteins?
modified proteins
What can be esterified by H3PO4?
the -OH group of ser, Tyr, and Thr
What are one of the methods used to study the secondary structure of AA?
x-ray
Immunoglobulin
provide resistance against bacterial and viral infection
