proteins part 2 Flashcards
____________ are biological catalyst –ex:
Pepsin, Trypsin
Enzymes
_______________ include antibodies
(Immunoglobulins) which are specific
protein molecules produced by
specialized cells of the immune system
in response to foreign antigens.
Defense Proteins include antibodies
(Immunoglobulins) which are specific
protein molecules produced by
specialized cells of the immune system
in response to foreign antigens.
- Membrane-bound immunoglobulin on the surface of immature and mature B cells
- First antibody produced in a primary response to an antigen
- First antibody produced by the fetus
- Efficient in binding antigens with many repeating epitopes, such as viruses
Classical complement activation
IgM (serum level-5%)
- Membrane-bound immunoglobulin on the surface of mature B cells
- No biological effector function known
igD (serum level-0.3%)
- Predominant antibody class in secretions (saliva, tears, breast milk) and mucosa
- First line of defense against infection by microorganisms
igA (serum level 7-15%)
- Most abundant class with four isotypes - IgGI, IgG2, IgG3, IgG4
Crosses the placenta
-Opsonization
igG (serum level-85%)
- Defense against parasite infections
- Associated with hypersensitivity reactions (allergies)
- Found mainly in tissues
igE (serum level- 0.02%)
_______________ carry material from place to another in the body. Ex: transferrin,
Hemoglobin and Myoglobin.
Transport Protein
____________ controls many aspects of cell
function, including metabolism and
reproduction. Ex: Insulin and Glucagon
Regulatory Protein controls many aspects of cell function, including metabolism and reproduction. Ex: Insulin and Glucagon
_______________ provide mechanical support to large animals and provide them with their outer coverings. Ex:
Keratin
Structural proteins provide mechanical support to large animals and provide them with their outer coverings. Ex:
Keratin
______________ are necessary for all forms of
movement. Ex. Actin and Myosin, Flagella of sperm cell.
Movement Proteins
______________ serves as source of Amino acids for embroyos or infants. Ex: Albumin and Casein
Nutrient Protein
• It is the amino acid sequence of the protein chain.
• This structure will determine its biological active form.
• It results from the covalent bonding between the amino acids in the chain
Primary Structure of Proteins
This level of structure describes the local folding pattern of the polypeptide backbone and is stabilized by hydrogen bonds between N-H and C=O groups. The most common are the orderly repeating forms known as the a helix and the b sheet.
Secondary Structure proteins
The most common type of Secondary structure may it be in coiled of helical conformation.
Special Feature:
-Every amide hydrogen and carbonyl oxygen associated with the peptide backbone is involved in a hydrogen bond when the chain coils into it.
- Every carbonyl oxygen is hydrogen bonded to an amide hydrogen four amino acids away in the chain.
a-Helix
– are structural proteins arranged in fibers or sheets that have only one type of secondary structure.
Fibrous Proteins
– are fibrous proteins that form
the covering (hair, nails and fur) of most land animals.
α-Keratins
The second common secondary structure in proteins resembles the pleated folds of drapery.
All the carbonyl oxygen and amide hydrogens in this are involved in hydrogen bonds, and the polypeptide chain is nearly completely
extended.
β-Pleated Sheet
What are the 2 Orientation of B-Pleated
form?
- Parallel
- Anti-parallel
• Beta sheets are ______ if the polypeptide strands run in the same direction,
N-terminus to C-terminus. The N-terminus of one beta strand will be opposite the N-terminus of the other beta strand.
the arrangement is less stable because the geometry of the individual amino acid molecules forces the hydrogen bonds
to occur at an angle, making them longer and thus weaker.
parallel
• Beta sheets are ___________ if the polypeptide strands run in opposite directions. The N- terminus of one beta strand will be opposite the C-terminus
of the other beta strand.
- in this the arrangement hydrogen bonds are aligned directly opposite each other, making for stronger and more stable bonds.
anti-parallel
________________________ forms when a polypeptide chain sharply reverses direction. This can occur in the presence of two consecutive proline residues, which create an angled kink in the polypeptide chain and bend it back upon itself.
Anti-parallel beta-pleated sheet forms when a polypeptide chain sharply reverses direction. This can occur in the presence of two consecutive proline residues, which create an angled kink in the polypeptide chain and bend it back upon itself.
- A protein whose structure is an antiparallel B-pleated sheet.
- The polypeptide chains of a B-pleated sheet are almost completely extended, and silk does not stretch easily.
Silk Fibroin