Question

1. (2 pts) Write a series of balanced equation concluding with the net equation for the synthesis of glucose (via gluconeogenesis) from aspartate 2. (3 pts) Write out the degradation pathway for the following amino acids (continue until you reach the product that the degradation family is named for e.g. pyruvate or a TCA intermediate). You must draw the structures and give the names of the enzymes and cofactors er ii. Gly (Draw the 2 principle pathways ii. Asn iv. Gln v. Met (this is a cyclic pathway - start and end with Met. You do not need to go the TCA intermediate) vi. Thr (Draw both pathways) 3. (2 pts) A. Draw the first two steps of the degradation of the branched chain amino acids indicate if they are ketogenic, glucogenic or both and give their principal degradation products B. Excess nitrogen accumulates in two amino acids during hyperammonemia draw the one step in the synthesis of each the amino acids that is relevant under excess ammonia conditions 4 (3 pts) A (2.5) Write out the synthesis pathway for the following amino acids (starting from either a glycolytic or TCA cycle intermediate). You must draw the structures and give the names of the enzymes and cofactors i. Ser ii. Ala ii. Asn iv. Gln v. Cys (starting with homocysteine) B. (0.5) What is the source of the nitrogen used in the synthesis of (i) Gln (ii) Asn

Answer 1

1)

Glucose phosphatase Glucose-6-phosphate PI Fructose phosphatase Fructose-1,6-bisphosphate Reactions p glycolysis, but in reve Phospheenolpyruvate GTP Phosphoenolpyruvate carboxykinase Oxaloacetate Aspartate aminotransferase Aspartate

3 A) The first step is transamination and the second step is oxidation decarboxylation reaction in degradation of branched chain amino acid like valine, isoleucine and leucine

e-Keto 8-methytvalerate r-Ketoisocaproate Ouidative decarbonylaton NADH sobutyryl CoA 2-Methylbutyryl CoA Isovaleryl CoA FADI2H) Acetyl Cok 2 NADH Propionyl Con L-methylmalonyl CoA Succinyl CoA

4 B)

i) Ammonia is the source of Nitrogen in Glutamine. Gln is synthesised from glutamate and ammonia by enzyme glutamine synthetase

ii)The precursor molecule for asparagine(Asn) synthesis is oxaloacetate(OAA). The enzyme transaminase converts OAA to aspartate by transferring the amino group from glutamate to oxaloacetate forming ?-ketoglutarate and aspartate.

So the Nitrogen source is glutamate for Asn