Chapter 18, Problem 17P

Interpretation Introduction

(a) Interpretation:

The folate structure which is the substrate for the enzyme that is inhibited by methotrexate and trimethoprim should be identified.

Concept Introduction:

The folate is used for naming of different forms of the vitamin such as folic acid and its congeners. This also includes tetrahydrofolic acid which is the activated vitamin form, folinic acid and folacin etc. Methotrexate is a folic acid competitor and cell cycle-specific antmetabolite. Trimethoprim is an antibiotic that is used in the treatment if bladder infections. The group attached to nitrogen in aliphatic chain mainly decides the role of folate structure.

Interpretation Introduction

(b) Interpretation:

The folate structure which has the most oxidizing one-carbon substituent should be identified.

Concept Introduction:

Most oxidizing one-carbon substituent will be the substituent which reduces others, this is in the case where nitrogen atom is attached to −CHO group which can be oxidized to COOH.

Interpretation Introduction

(c) Interpretation:

The folate structure which is used in the conversion of serine to glycine should be identified.

Concept Introduction:

The structure of serine amino acid is as follows:

And that of glycine is as follows:

Serine and glycine are linked biosynthetically, they are important in the synthesis of proteins, lipids and nucleic acids. The biosynthesis of serine/ glycine affects the antioxidant capacity of cell.

Interpretation Introduction

(d) Interpretation:

The folate structure which transfers its one carbon substituent to a B₁₂coenzyme should be identified. The amino acid synthesized as the end result of this reaction should be identified.

Concept Introduction:

Vitamin B₁₂ is also known as cobalamin. It is a water-soluble vitamin which is important in the cell metabolism. It is important for normal functioning of the nervous system. It is one of the 8 vitamins which is large, and the structure is most complicated. It consists of rare element cobalt.

Interpretation Introduction

(e) Interpretation:

The folate structure which is the coenzyme for the thymidylate synthase reaction should be identified.

Concept Introduction:

Thymidylate synthase is an enzyme which is used in the catalytic conversion of deoxyuridine monophosphate to deoxythymidine monophosphate. In DNA, thymidine is one of the nucleotides. Thymidylate synthase inhibition can results imbalance of deoxynucleotides and increase in the level of dUMP which can cause DNA damage.

Interpretation Introduction

(f) Interpretation:

The folate structure which is not known to exist in nature should be identified.

Concept Introduction:

The folate is used for naming of different forms of the vitamin such as folic acid and its congeners. This also includes tetrahydrofolic acid which is the activated vitamin form, folinic acid and folacin etc.

Interpretation Introduction

(g) Interpretation:

The folate structure which is used in purine nucleoside synthesis should be identified.

Concept Introduction:

Purine nucleotides are components of DNA and RNA that plays important role in cellular functions. Nucleotide is a compound which consists of nucleoside linked with a phosphate group. They are basic structural unit of DNA or RNA.