A group of enzymologists wanted to find a form of alkaline phosphatase capable o

Question

A group of enzymologists wanted to find a form of alkaline phosphatase capable of maintaining high specific activity at high temperatures. First, they purified alkaline phosphatase from bacteria that live in hot springs. Next, they studied the effects of pH and temperature on specific activity. Finally, because alkaline phosphatase is a metalloprotein, they evaluated the effects of different metal ions on specific activity. 1. What reaction does alkaline phosphatase catalyze? Identify the substrate (type of molecule), any other reactants and the product(s). 2. What organisms make alkaline phosphatase enzymes? 3. Define specific activity and indicate units. Be sure you distinguish between

Explanation / Answer

1. Glucose - 6- phosphate is dephosphorylated by alkaline phosphatase. The product is glucose. It catalyses many dephosphorylation reactions, like the removal of phosphate from proteins and nucleotides.The enzyme works best in alkaline conditions, hence its name. 2. Bacteria makes alkaline phosphatase enzyme. 3. Specific activity is a term used in measuring enzyme kinetics (rate of reaction of an enzyme with a particular substrate). This term is defined as the amount of substrate the enzyme converts (reactions catalyzed), per mg protein in the enzyme preparation, per unit of time. Specific activity is a measure of enzyme purity. The value becomes larger as an enzyme preparation becomes more pure, since the amount of protein (mg) is typically less, but the rate of reaction stays the same (or may increase due to reduced interference or removal of inhibitors). Examples: The specific activity of the isolated enzyme was measured at 150 umoles/min/mg protein before purification and 800 umoles/min/mg, after purification. 4. Metalloprotein is a generic term for a protein that contains a metal ion cofactor.[1] A large fraction of all proteins are members of this category, so the area is very large.

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