Niacin: Metabolism to NAD and NADP

The video tutorial explains niacin, also known as vitamin B3, and its role in human metabolism. It covers the synthesis of niacin through the Dinovo pathway and its conversion into active coenzymes NAD and NADP. The tutorial also discusses the convergence of Dinovo and dietary pathways, the salvage pathway for NAD synthesis, and methods for detecting NADH using UV VIS spectrophotometry. An example of lactate dehydrogenase is used to illustrate enzyme activity measurement.

What is a unique feature of niacin compared to other B vitamins?

• It is the most abundant vitamin in the diet.

• It is only found in animal products.

• It does not require any transformation to become active.

• It can be synthesized de novo in humans.

Which amino acid's breakdown is involved in the de novo synthesis of niacin?

• Tryptophan

• Valine

• Lysine

• Methionine

What is the role of quinolinic acid in the niacin synthesis pathway?

• It is a starting material for niacin synthesis.

• It is the final product of the pathway.

• It is a side product with no role in the pathway.

• It is an intermediate that leads to nicotinate mononucleotide.

Which enzyme catalyzes the adenylation of nicotinate mononucleotide?

• Nicotinate phosphoryl transferase

• NAD kinase

• Quinolinic acid phosphoryl transferase

• Nicotinate mononucleotide adenosyl transferase

What is the primary difference between NAD and NADP?

• NADP is not bioactive.

• NAD can transfer only one electron.

• NADP is synthesized only in plants.

• NADP has an additional phosphate group.

Why is NADH measured at 340 nm using UV-VIS spectrophotometry?

• NADH absorbs light at this wavelength, while NAD does not.

• It is the only wavelength available for measurement.

• NAD absorbs more light at this wavelength.

• Both NAD and NADH absorb equally at this wavelength.

In the lactate dehydrogenase reaction, what happens to NAD?

• It is converted to NADP.

• It is oxidized to NADH.

• It is reduced to NADH.

• It remains unchanged.