Delta-Aminolevulinate Synthase (ALA Synthase): Physiology, Biochemistry, and Organic Mechanism

The video tutorial explains the synthesis of heme, focusing on the role of delta aminolevulinic acid synthase (ALA synthase) as the committed step in the process. It discusses the enzyme's function, regulation, and the impact of its deficiency, which can lead to disorders like X-linked sideroblastic anemia. The tutorial also covers the enzyme's mechanism, highlighting the importance of pyridoxal phosphate and the regulation of ALA synthase by energy charge and other factors.

What is the committed step in the synthesis of heme?

• Formation of cytochrome P-450

• Action of delta aminolevulinic acid synthase

• Synthesis of myoglobin

• Conversion of glycine to succinyl CoA

Which condition is associated with a deficiency of delta aminolevulinic acid synthase?

• Porphyria

• X-linked sideroblastic anemia

• Hemochromatosis

• Iron deficiency anemia

What is the role of pyridoxal phosphate in Ala synthase activity?

• It is a product of the reaction

• It inhibits the enzyme activity

• It is a cofactor required for decarboxylation

• It acts as a substrate for heme synthesis

What is the effect of low energy charge on Ala synthase activity?

• It inhibits the enzyme

• It has no effect

• It increases enzyme activity

• It decreases enzyme activity

Which of the following is a potent upregulator of Ala synthase?

• Iron

• Hemin

• Phenobarbital

• Vitamin B6

What is the role of heme in the regulation of Ala synthase?

• It is a substrate for the enzyme

• It enhances enzyme activity

• It is an allosteric inhibitor

• It acts as a cofactor

How many glycines are required to synthesize one molecule of heme?

• 4

• 6

• 8

• 10

What is the primary reason for tightly regulating heme synthesis?

• To prevent excess heme accumulation

• To increase oxygen carrying capacity

• To conserve energy from the TCA cycle

• To enhance cytochrome P-450 activity

What is the function of pyridoxal phosphate in the mechanism of Ala synthase?

• It forms a shift base with glycine

• It acts as an electron donor

• It stabilizes the enzyme structure

• It chelates iron in the reaction

Which molecule is transported out of the mitochondria after its formation by Ala synthase?

• Cytochrome C

• Delta aminolevulinic acid

• Succinyl CoA

• Porphobilinogen