Question

Question: Name the coenzymes that

a. allow electrons to be delocalized.

b. are oxidizing agents.

c. provide a strong base.

d.donate one-carbon groups

Short answer

(a) NAD⁺, NADP^-, FAD, thiamine pyrophosphate, carboxybiotin, pyridoxal phosphate allow electrons to be delocalized.

(b) Thiamine pyrophosphate, lipoate, biotin, pyridoxal phosphate and coenzyme B₁₂are oxidizing agents.

(c) Vitamin KH₂ provides a strong base.

(d) Tetrahydrofolate donates one-carbon groups

Step-by-step solution

Oxidizing Coenzyme

Oxidizing agent refers to a substance that tends to oxidize other substances. There are commonly two oxidizing coenzymes used by enzymes to catalyze oxidation reactions. Nicotinamide adenine dinucleotide (NAD⁺)catalyzes oxidation reactions and Flavin adenine dinucleotide (FAD),is very much similar to NAD⁺. It is a coenzyme used to oxidize a substrate. As its name represents, FAD is a dinucleotide in which one of the heterocyclic components is Flavin and the other is adenine.

A rough guideline is that NAD⁺ is the coenzyme used in enzyme-catalyzed oxidation reactions involving carbonyl compounds (for example, alcohols being oxidized to ketones, aldehydes, or carboxylic acids), whereas FAD is the coenzyme used in other types of oxidations.

Vitamin KH2

Fat-soluble vitamin K plays a vital role in blood coagulation. The blood clotting proteins formed in the liver in the inactive form are converted to the active form by their post-translational modification, which involves vitamin KH₂ i.e. Vitamin K (Hydroquinone).

The mechanism for the vitamin –catalyzed carboxylation of glutamate had puzzled chemists because the γ-proton that must be removed from glutamate before reacting with CO₂ is not very acidic. So, therefore, the mechanism must involve the creation of a strong base that can remove this proton.

Identify the following Co-enzymes

(a) NAD⁺, NADP^-, FAD, thiamine pyrophosphate, carboxybiotin, and pyridoxal phosphate allow electrons to be delocalized.

(b) Thiamine pyrophosphate, lipoate, biotin, pyridoxal phosphate and coenzyme B₁₂are oxidizing agents.

(c) Vitamin provides a strong base. It is because the mechanism for the vitamin –catalyzed carboxylation of glutamate had puzzled chemists, because the γ-proton that must be removed from glutamate before reacting with CO₂ is not very acidic. So, therefore, the mechanism must involve the creation of a strong base that can remove this proton.

(d) Tetrahydrofolate is involved in a one-carbon transfer that is bound to position N₅, N₁₀ or both. Molecules of Serine, glycine, histidine, and tryptophan are the major sources of one-carbon pool as they donate single carbon to THF in various oxidation states and can be reduced or oxidized. Thus, Tetrahydrofolate donates one-carbon groups.