Proteins Flashcards
Functions of proteins
Antibodies, enzymes, messenger molecules, receptor molecules, structural components (collagen) and transport/storage molecules such as hemoglobin or albumin.
What does each amino acid contain
- Amino functional group (N terminus group) H2N which is to the left of the alpha carbon. Base.
- Hydrogen (above alpha carbon)
- R chain (radical= varying) which is below the alpha carbon
- Carboxyl functional group COOH (C terminus group) to the right of the alpha carbon. Acid.
Amino group structure and property
R- NH2
Polar accepts H+ to form NH3
BASE ACCEPTS
Carbonyl structure and property
O
||
R-C-R(or H)
Polar
Carboxyl structure and property
O
||
R-C-O-H
Polar, ionizes to release H+
ACID RELEASES
A base ___ H+ and an acid ___ H+
a base accepts and an acid releases
Hydroxyl structure and property
R-O-H
Polar
Methyl structure and property
CH3 Nonpolar
Phosphate structure and property
R- PO3H2
Polar, ionizes to release H+ (Acid)
Sulfhydryl
R-S-H Polar, forms disulfide bonds
What functional groups indicate an acid
Anything that is ok with releasing an H+.
Carboxyl group and phosphate group
(Aspartic acid and glutamic acid)
both are also polar
What functional groups indicate bases
Anything that wants to accept an H+.
Amino group (R-NH2)
Also polar
Condensation reactions
one of two reactions that occur in order to form long chains of amino acids. Either the joining of 2 molecules by dehydration (loss of water)
or the splitting of 2 molecules by hydrolysis (gain of water)
Where do peptide bonds form on amino acids
They form between a carboxyl group on one and the amino group on another by dehydration reaction
Primary structure bonds
Peptide, covalent
Secondary structure bonds and examples
H bonds between alpha helix backbone and beta sheet backbone (parallel or antiparallel)
Tertiary structure bonds
- H bones
- Ionic bonds
- Van der waals
- hydrophobic interactions (clustering of hydrophobic molecules away from water)
- disulfide bridges
Gives an overall 3D shape
Quaternary structures
Multi-subunit proteins such as dimers (2 polypeptides) or tetramers (4 polypeptides)
Based on the tertiary/quaternary structure, proteins are grouped in 2 general classes
Fibrous and globular
Fibrous proteins are elongated, insoluble in water, tend to have structural roles such as collagen or elastin
Globular proteins are compact and spherical, are amphipathic, tend to have roles other than structural such as enzyme, Antibodies, hemoglobin
Characteristics and roles of fibrous tertiary/quaternary proteins
Fibrous proteins are elongated, insoluble in water, tend to have structural roles such as collagen or elastin
Characteristics and roles of globular tertiary/quaternary proteins
Globular proteins are compact and spherical, are amphipathic (hydrophilic on outside and hydrophobic on inside AKA insoluble in water), tend to have roles other than structural such as enzyme, Antibodies, hemoglobin
