Question

1. Compare coenzymes with substrates. Explain how they both collaborate in enzyme catalysis.

2. High levels of ammonia (NH3) are toxic to mammals. One reason is that ammonia bonds with alphaketoglutarate in the citric acid cycle, forming the amino acid glutamate. This removes alphaketoglutarate from the Krebs cycle. Explain what consequences this will have for the cell.

3.  Pyruvate + NADH + H+ à lactate + NAD+

Name the oxidizing agent in the above reaction. Explain

4. Trace the steps of a carbon atom from a starch molecule contained in the Donut you just eat until it ends up in a muscle protein.

Please answer ASAP!!

Thank you.

Answer 1

Answer :

1) The coenzymes are organic substances which help the enzyme in their action . They act as substrates to accept or donate some atoms , radicals etc. This may be organic substances like NAD, NADP, CO A , Coenzyme Q,TPP etc all this have a common name, called cofactor.they are non protein compounds needed for functioning of an enzyme , are less specific and small .

Whereas a substrate is a molecule acted upon by an enzyme which is located into the active site of the enzyme or place that allows, weak bonds to formed between two molecules. More specifically a substrate to which another substance is applied, we called it as a substrate.

A coenzyme is a catalyst that is converted to a new product concomitant with each turnover of substrate.

3) In that reaction NAD+ acts as a oxidizing agent.

It acts as the because it acts as a hydrogen acceptor and therefore oxidized it. Accept hydrogen from lactic acid and convert

NAD+》NADH + H+ .

2) High levels of NH3 are toxic to mammals. The reason is that NH3 bond with alpha ketoglutarate in TCA cycle forms glutamate in anaplerotic reaction which in transamination to form glutamate to alpha ketoglutarate.

In anaplerotic reaction, mitochondrial L-glutamate dehydrogenase may use NAD+ to oxidized L- glutamate to alpha iminoglutarate which is hydrolysis in to NH3 and alpha ketoglutarate.

Glutamate + NAD+ + H2O 》 Alpha ketoglutarate + NH4+ +NADH+ H+

In still another reaction in mitochondria, glutamate transaminase forms alpha ketoglutarate from L- gutamate by exchanging the amino group of the latter with the ketonyl-O of some alpha keto acid such as pyruvate.

Glutamate + pyruvate 》 alpha ketoglutarate + alanine.