OChem Chapter 12,14 Test

Fibrous Functions
structure and contractive
Fibrous Structure

key: hiedrical structure

 

mostly non-polar amino acids are coiled together into super structures

Globular Functions

Metabolic Work:

-Catalysis

-Transport

-Regulation

-Protection

Globular Structure
Soluble (hydrophilic side chains)
Fibrous Solubility
insoluble in water
Fibrous Structure (Primary…)

  • No tertiary
  • Usually have quaternary

α-Keratines (where?)

hair, skin, nails, horns, hoofs, wool

(Fibrous Proteins)

Strength of Fibrous Proteins
h-bonding and disulfide bridges between peptide chains
Hemoglobin Structure

4 polypeptide chains (2-α and 2-β)

 

alpha-helices separated by beta-turns

Hemoglobin (where?)
blood
Myoglobin Structure
Only 1 polypeptide chain
Protein function ulitmately depends on…
primary structure (amino acid sequence)
Genetic Mutation
An alteration in the DNA structure of a gene that may in turn produce a change in the primary structure of a protein
Sickle-cell Hemoglobin

Region critical to binding oxygen are NOT changed

 

Sickling is the aggregation of the hemoglobins (hydrophobic attractions between the hydrophobic pocket and residue 6 (Val))

Sickle-cell Anemia (where?)

Western Africa

likely because of high incidence of malaria

Denaturation
Loss of native conformation brought about by a change in envirnmental conditions, resulting in a loss of physiological function
Denaturation alters which structures
Alters secondary, tertiary and quaternary structures
Digestion

Breaks peptide bonds and alters primary structure

 

Not denaturation

Denaturation (Globular vs. Fibrous)
Globular protein have weaker secondary forces and thus are denatured easier.
7 Methods of Denaturation

  1. Increase Temp
  2. UV and ionizing Radiations
  3. Mechanical Energy
  4. Changes in pH
  5. Organic Chemicals
  6. Salts of Heavy Metals
  7. Oxidizing and Reducing Agents

Increased Temp

Increased motion disrupts non-covalent attractions

 

Example: cooking and sterilization

UV and Ionizing Raditions

Causes chemical reactions

 

Example: X-ray

Mechanical Energy
Example: Whipping Eggs
Changes in pH
Affects salt bridges
Organic Chemicals

Affects hydrophoic interactions

 

Example: Rubbing Alcohol

Salts of Heavy Metals

"Pb2+, Hg2+ and Ag+ react with sulfdryl groups and forms metal disulfide bridges

 

Example: Mecury Poisioning"

Oxidizing and Reducing Agents

Oxidizing: forming disulfide bridges

Reducing: breaking disulfide bridges

 

Example: Perm

Matabolism Functions

  • Obtain energy in chemical form by degradation of nutrients
  • Convert a wide vareity of molecules into a few precursor molecules
  • Synthesize cell molecules
  • Produce or modify biomolecules necessary for specific functions in specialized cells

Catabolism

Biochemical degradation/break-down of energy-containing compounds (energy releasing)

 

Exampe: Combustion of C6H12O6, opposite of photosynthesis

Catabolism Process

Nutrient molecules

Precursor Molecules

Acetyl CoA

Water and Carbon Dioxide

ATP

adenine triphosphate

 

 Used for energy required processes

NADH

nicotinamide adenine…

 

Used to make ATP

Stages 2 & 3
use much of energy to create energy carrier molecules (ATP and NADH)

Catabolism

(oxidation or reduation)

Oxidation process

 

low energy → high energy

Anabolism

(oxidation or reduation)

Reduction process

 

high energy → low energy

Enzymes

  • Organic Catalyst
  • Can be denatured
  • Proteins

Active Site

  • Where the substrate binds
  • Has anchor points

Anchor Points

  • Hold the substrate in place
  • Use IMF to do so

Substrate
Reactant molecule
Complementarity
Enzymes highly specific to their substrates
Induced Fit
Protein/enzyme changes space as the substrate binds
Lock and Key
Enzyme doesn’t change shape, fits directly into active site
True Substrate
the reactant that in supposed to react
Substrate Analog
a molecule similar to the true substrate (size, shape, charge, polority)
Competitive Inhibitor
Substrate analog that binds in the active site (binds but doesn;t react)
Non-competitive Inhibitor
;alosteric;-a molecule that binds to a region other than the active site causing the conformation change which prevents the true substrate from binding
Cofactors/Coenzymes
ions/molecules that are needed to complete a protein’s structure so that in can function
Apoenzyme
(apoprotein) polypeptide portion
Haloenzyme

Entire functional protein/enzyme

 

Cofactors/coenzymes + apoenzyme = haloenzyme

Riboflavin
in FAD
Niacin
in MAD
Covalent Modification
enzyme activity is regulated by covalently attaching a group which either activates or deactivates that enzyme’s activity
Feedback Inhibition
when the product of one reaction serves as an inhibitor for a previous reaction
Regulatory Enzymes
enzymatic activity controlled by binding of activators/inhibitors
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