Proteins
o Amino Acids and Polymerization
Structure
H- hydrogen atom
NH2- amino functional group
COOH2- carboxyl functional group
Distinctive R group (side chain)
How they behave in water
They ionize
o Causes the amino group to act as a base (forms NH3+)
o The carboxyl group acts as acid (COO+)
Side chains
Represents the part of the amino acid core structure that each of the 20
different amino acids unique
Functional groups affect reactivity
o Amino acids with (SH) in the side chain can form (S-S) disulfide
bonds that help link different parts of large proteins
, o Some functional groups only have H and C atoms, which rarely
participate in chemical reactions (mean they depends primarily on
their size and shape)
Polarity and Charge of R-groups Affect Solubility
o Hydrophilic
Polar and electrically charged R-groups
Dissolve easily in water
Serine, Threonine, and Cysteine
Acidic: aspartic acid, glutamic acid
Basic: lysine, arginine, histidine
o Hydrophobic
Non-polar, lack charge, highly electronegative
Coalesce in solution
Glycine, Alanine, and Valine
Proline, tryptophan, phenylalanine
o 3 things to look at
Does the R-group have – charge
If yes, then its acidic and has lost proton
Does the R-group have + charge
If yes, then its basic and has accepted proton
If the R-group has NO charge, does it have an O atom?
If yes, then the highly electronegative O will form a
polar covalent bond, making it uncharged polar
If NONE of the above are true
It is a nonpolar amino acid
How amino acids link to make proteins
o The C-N covalent bond that forms from condensation is a PEPTIDE
BOND
o Peptide bonds
Forms in ribosomes
Usually stable
C-N form a double bond
C-O single bond
Have some of the same characteristics as double bonds
Planar
Limiting movement of the atoms that are in the
peptide bond
R-group orientation
The side chains of the residue extend to backbone,
interact with others and water
Directionality
Amino group on one end of the backbone and a
carboxyl group on the other
N-terminus (amino terminus)
o Amino Acids and Polymerization
Structure
H- hydrogen atom
NH2- amino functional group
COOH2- carboxyl functional group
Distinctive R group (side chain)
How they behave in water
They ionize
o Causes the amino group to act as a base (forms NH3+)
o The carboxyl group acts as acid (COO+)
Side chains
Represents the part of the amino acid core structure that each of the 20
different amino acids unique
Functional groups affect reactivity
o Amino acids with (SH) in the side chain can form (S-S) disulfide
bonds that help link different parts of large proteins
, o Some functional groups only have H and C atoms, which rarely
participate in chemical reactions (mean they depends primarily on
their size and shape)
Polarity and Charge of R-groups Affect Solubility
o Hydrophilic
Polar and electrically charged R-groups
Dissolve easily in water
Serine, Threonine, and Cysteine
Acidic: aspartic acid, glutamic acid
Basic: lysine, arginine, histidine
o Hydrophobic
Non-polar, lack charge, highly electronegative
Coalesce in solution
Glycine, Alanine, and Valine
Proline, tryptophan, phenylalanine
o 3 things to look at
Does the R-group have – charge
If yes, then its acidic and has lost proton
Does the R-group have + charge
If yes, then its basic and has accepted proton
If the R-group has NO charge, does it have an O atom?
If yes, then the highly electronegative O will form a
polar covalent bond, making it uncharged polar
If NONE of the above are true
It is a nonpolar amino acid
How amino acids link to make proteins
o The C-N covalent bond that forms from condensation is a PEPTIDE
BOND
o Peptide bonds
Forms in ribosomes
Usually stable
C-N form a double bond
C-O single bond
Have some of the same characteristics as double bonds
Planar
Limiting movement of the atoms that are in the
peptide bond
R-group orientation
The side chains of the residue extend to backbone,
interact with others and water
Directionality
Amino group on one end of the backbone and a
carboxyl group on the other
N-terminus (amino terminus)
