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Protein Structure and Function

Terms in this set (104)

Protein structure
•3-D shape - determines function
-Variety of shapes and properties
-Array of function
Proteins grouped into functional classes such as
-Structural
-Scaffold
-Enzymes
-Membrane transport
-Regulatory / signaling
Protein Activities
binding, catalysis, folding
Binding
-Other proteins, DNA, other molecules, ions
-Bind by complementation
catalysis
Catalysis of cellular processes
folding
Form channels/ pores
folding makes it easier to
identify proteins and determine their function
Protein Structure determines
function
protein structure is determined by
amino acid sequence and non-covalent interaction
four levels of organization of protein structure
-A. Primary structure - linear
-B. Secondary structure - a-helix and b-sheets
-C. Tertiary structure - more stable; can have domains
-D. Quaternary structure- More than one polypeptide associate together
Primary Structure of Proteins
-Linear chain of amino acids linked together by peptide bonds
-Bonds between amino group and carboxyl group
-Side chains determine distinct properties of proteins
Size in molecular weight or mass - Daltons
Secondary Structure of Proteins
-Main secondary structures are a-helix, b-sheets, b-turn, irregular structures, and random coil.
-The polypeptide chain folds and is held by hydrogen bond between the amide and the carbonyl group
-60% are a-helix and b-sheets
a-helix
amino and carbonyl groups of the backbone are hydrogen bonded except at the beginning and the end
Each turn has 3.6 residues and 0.54 nm per turn
Vary in how tightly they are coiled
Hydrophilic side chains make the protein water soluble and vice versa
b-sheets
5-8 residues in length
Packed together with hydrogen bonds between adjacent b chain and perpendicular to them.
Peptide bonds determine direction of b sheet (amino-carbonyl terminal).
Role to form a membrane pore with hydrophilic core
b-turns
Made of 4 residues covering the bends
End residues bond together and stabilize the structure
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