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PROTEIN STRUCTURE
Protein Structure
 Primary Structure – The order of amino acids.
 Secondary Structure – The coiling or folding of the
primary structure. This is facilitated by the carbonyl
groups forming hydrogen bonds with the N-H
groups.
 Tertiary Structure – The folding of the coil or sheet.
The form of the folding is determined by the side
chains on the amino acids. Thus the order, or primary
structure comes into effect here.
 Quaternary Structure – Not always present, this is a
complex formed by multiple tertiary forms. This is
often formed around metal ions.
Summary of Structures
Secondary Structure – Alpha helix
Secondary Structure – Alpha Helix
Secondary Structure - Sheet
 Sheets are formed by primary chains
attached by the same H-bonds as in the helix
Tertiary Structure
 Various interactions contribute to the
formation of the structure of a protein.
 Di-sulfide bonds
 Salt-ion interactions, called salt bridges
 Hydrogen Bonding
 Hydrophobic groups interacting.
Tertiary Structure
Quaternary Structure
Antibodies
Denaturing
 To “denature” a protein is to break up it’s
structure. Largely, it is the tertiary structure that
is disrupted, however, any disruption of
secondary, tertiary or quaternary structure
applies.
 Denaturing may be accomplished by:
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Heat
Acid or base
Heavy Metals
Agitation
Organic compounds that interact with side chains
Enzymes
 Working proteins are functional in a myriad of
ways. Some proteins act as structural
elements such as that in hair or collagen.
Others function as enzymes. These depend
very heavily on shape as the operate via a
lock and key mechanism.
 This mechanism can be disrupted by similar
molecules that fit within the proteins. These
are called inhibitors.
 Computer Animation of ATP Hydrolysis
Enzymes and Inhibition
Advanced Glycosidic Products, (AGE’s)
 Advanced Glycosidic End Products, (AGE’s), also known as Maillard
Reaction Products are known to effect all tissue proteins and DNA.
 Originally recognized in diabetics, then in normal individuals, AGE’s
play a major role in diabetic complications including blindness,
arteriosclerosis, joint stiffness, kidney disease and are correlated
with chronic high blood sugar, a precursor to adult onset diabetes.
 AGE’s are a principle components in what are thought to be normal
aging processes. Characteristics associated with aging, both
internal and external, are affected by blood sugar levels.**
Krajcovivova-Kudlackova M. Physiol. Res. 51 313 (2002) and Baynes J.W. et. al. “The Mailard Reaction in
Aging, Diabetes and Nutrition” publ. Alan R. Liss, N.Y.
Formation of cross-linked proteins
Cerami A. et. al. “Glucose and Aging” Sci. Amer. 256 90 (1986)