NEW!!! L-Lactate Dehydrogenase: Physiology, Biochemisty, and Mechanism

The video tutorial explores the mechanism of lactate dehydrogenase, an enzyme crucial in anaerobic fermentation. It provides background on glycolysis, the role of NADH, and the impact of oxygen levels on cellular metabolism. The tutorial explains how lactate dehydrogenase helps regenerate NAD+ under low oxygen conditions, allowing glycolysis to continue. The video also details the enzyme's organic mechanism, including the conversion of pyruvate to lactate and vice versa, highlighting the enzyme's role in maintaining cellular energy balance.

What is the primary role of lactate dehydrogenase in humans?

• To transport oxygen in the blood

• To break down fatty acids

• To convert pyruvate to lactate under anaerobic conditions

• To synthesize glucose

What does anaerobic fermentation imply about oxygen levels?

• Low oxygen levels

• No oxygen present

• High oxygen levels

• Normal oxygen levels

Why is NADH critical in the process of glycolysis?

• It breaks down pyruvate

• It directly produces ATP

• It is a reduced coenzyme that is transported into mitochondria

• It acts as a substrate for glucose

What happens to cytochrome C oxidase under low oxygen conditions?

• It increases its activity

• It converts lactate to pyruvate

• It produces more ATP

• It shuts down due to lack of substrate

How does lactate dehydrogenase help in regenerating NAD?

• By synthesizing ATP

• By reducing pyruvate to lactate

• By oxidizing glucose

• By converting lactate to pyruvate

What is the waste product formed when pyruvate is reduced by lactate dehydrogenase?

• Glucose

• ATP

• Acetyl CoA

• Lactate

What is the role of the histidine residue in the active site of lactate dehydrogenase?

• To transport electrons

• To bind NADH

• To act as a general acid-base catalyst

• To stabilize the carboxylate group

What happens to the aromaticity of the pyridine ring during the reduction by NADH?

• It is lost

• It is regenerated

• It is unchanged

• It is converted to a hydroxyl group

In the conversion of lactate back to pyruvate, what is the role of NAD+?

• It stabilizes the enzyme

• It is converted to ATP

• It acts as an oxidizing agent

• It acts as a reducing agent

What is the main function of lactate dehydrogenase under anaerobic conditions?

• To regenerate NAD+ by converting pyruvate to lactate

• To produce glucose

• To transport oxygen

• To synthesize proteins