Purine Catabolism: Conversion of Hypoxanthine to Uric Acid

The video tutorial explores the catabolism of nucleic acids, focusing on purine breakdown. It begins with adenosine conversion to inosinate and hypoxanthine, followed by the conversion of hypoxanthine to uric acid using xanthine oxidase. The enzyme's mechanism is detailed, highlighting the role of coenzymes like molybdenum coenzyme, FAD, and NAD. The tutorial also covers electron transfer processes and the regeneration of coenzymes, emphasizing the enzyme's dual activity in different settings.

What is the initial molecule in purine catabolism discussed in the video?

• Thymidine

• Cytidine

• Adenosine

• Guanosine

Which enzyme is responsible for converting hypoxanthine to uric acid?

• Xanthine oxidase

• Adenosine deaminase

• Uricase

• Nucleoside phosphorylase

What is the functional group change involved in the conversion of hypoxanthine to xanthine?

• Ester to ether

• Amide to amine

• Shift base to amide

• Carboxyl to hydroxyl

Which coenzyme is abbreviated as MOCO?

• Molybdenum coenzyme

• Flavin adenine dinucleotide

• Coenzyme Q

• Nicotinamide adenine dinucleotide

What role does molybdenum play in xanthine oxidase?

• Transitions between oxidation states

• Catalyzes phosphorylation

• Binds to DNA

• Acts as a ligand

What is the initial oxidation state of molybdenum in the xanthine oxidase mechanism?

• +4

• +5

• +6

• +2

Which molecule is produced as a result of the electron transfer in xanthine oxidase?

• GTP

• FADH2

• ATP

• NADH

What happens to FADH- in the presence of NAD+ in the active site?

• It forms water

• It regenerates FAD

• It produces ATP

• It binds to DNA

What alternative molecule can xanthine oxidase use to regenerate FAD in a lab setting?

• Hydrogen peroxide

• Molecular oxygen

• Carbon dioxide

• Nitrogen gas

What is the final product of purine catabolism discussed in the video?

• Urea

• Allantoin

• Ammonia

• Uric acid