Basic Enzymology • Characteristics and capabilities of a bacterium – Genotype: Coded for in the DNA including plasmids – Genes code for proteins – Proteins are or are responsible for the traits of the cell – Examples: •Sugars present on O-antigen of LPS •Whether the bacterium has a flagellum •Being able to use the sugar sucrose as a nutrient – Mostly these proteins are enzymes •All enzymes are proteins (except for some RNAs) 1
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Basic Enzymology Characteristics and capabilities of a bacterium –Genotype: Coded for in the DNA including plasmids –Genes code for proteins –Proteins.
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Basic Enzymology
• Characteristics and capabilities of a bacterium– Genotype: Coded for in the DNA including plasmids– Genes code for proteins– Proteins are or are responsible for the traits of the cell– Examples:
• Sugars present on O-antigen of LPS• Whether the bacterium has a flagellum• Being able to use the sugar sucrose as a nutrient
– Mostly these proteins are enzymes• All enzymes are proteins (except for some RNAs)
1
Enzymes
• Have a distinct 3D shape essential for activity
• Are biological catalysts– Speed up the rate of a chemical reaction
• Lower activation energy by holding molecule in a favorable place
– Not consumed or permanently changed– Highly specific
• Will react some with similar molecules especially if their concentration is high.
2
3Enzyme function depends on shape
Substrates
Product
Enzyme brings substrates together in active site, increasing the rate at which they react.
In allosteric site, inhibitor is not reacted, but causes a shape change in the protein. The substrate no longer fits in the active site, so it is not chemically changed either.
ghs.gresham.k12.or.us/.../ noncompetitive.htm
9More about Enzymes
• Sometimes an enzyme needs help– Protein alone = apoenzyme– Helper molecule: cofactor
• Could be inorganic like a metal ion (Fe+2)• Could be organic coenzyme (like CoA, NAD)
– Apoenzyme + cofactor = holoenzyme.– Cofactors have an effect on nutrition
• Bacteria have certain mineral requirements.• Vitamins are cofactors that are needed in the “diet”.
There is a standard free energy change (both reactants and products at 1.0 M) that indicates which direction the reaction would go.
Concentration important! 14
In the example, if another reaction removed lactate, the concentration would be kept low, driving the reaction left to right.This also lowers ∆G, meaning reaction goes left to right.