Lecture 33

Question 1

What is the necessary cofactor of amino transferases?

Answer 1

pyridoxal phosphate (active form of B6)

Question 2

What is the most commonly used pair in Amino Transferase reactions?

Answer 2

glutamate/alpha keto-glutarate

Question 3

What does alanine become in a transaminase rxn? aspartate?

Answer 3

pyruvate, oxaloacetate

Question 4

aminotransferases are found in practically all tissues - which two are the most and why?

Answer 4

muscle (glucoalanine cycle - for gluconeogenesis) and liver (urea cycle)

Question 5

What enzyme is used to liberate NH4 from glutamine?

Answer 5

glutaminase

Question 6

What enzyme is used to synthesize glutamine using NH4?

Answer 6

glutamine synthetase

Question 7

What enzyme is used to tear NH4 off of glutamate (and possibly put it back on…)?

Answer 7

glutamate dehyrdogenase

Question 8

Does intestinal bacteria produce NH4?

Answer 8

yes

Question 9

What enzyme is used to convert other amino acids to glutamate?

Answer 9

aminotransferases

Question 10

What enzyme is used to liberate NH4 from other amino acids?

Answer 10

amino acid oxidases

Question 11

What type of reaction is the glutamate dehydrogenase reaction? What is utilized in formation of glutamate? What is utilized and released in opposite reaction (formation of alpha-ketoglutarate)?

Answer 11

• oxidation-reduction
• NH4 and NADPH
• NAD+ (NH4 released)

Question 12

What is utilized in the glutamine synthetase reaction?

Answer 12

glutamate + ATP + NH4 = glutamine + ADP + Pi

Question 13

What happens in the glutaminase rxn?

Answer 13

glutamine + H2O = glutamate + NH3

Question 14

What must happen to amino acids if they are going to be used by anything but protein synthesis?

Answer 14

The amino group must be removed

Question 15

What enzyme couples amino acids onto their specific tRNAs for protein synthesis?

Answer 15

-Amino acyl tRNA synthetase

Question 16

What combines with the amino acids to produce Aminoacyl-AMP? What then replaces the AMP?

Answer 16

• ATP

- tRNA

Question 17

What are the “sinks” for non-essential AA?

What are they used for? Arrows double or single sided?

Answer 17

• 3-phosphoglycerate, pyruvate, a-ketoglutarate, OAA
• glycolysis, gluconeogenesis, TCA cycle
• double

Question 18

What are the sinks for Essential AA? Are arrows double or single?

Answer 18

• 3-phosphoglycerate, pyruvate, acetoacetate>acetyl CoA, a-ketobutyrate>propionyl CoA>succinyl CoA, fumarate
• single

Question 19

What swaps amino groups from alpha-keto acids to amino acids? What carbons are the groups found on?

Answer 19

aminotransferases, C2

Question 20

How many aminotransferases are there?

Answer 20

18

Question 21

What does alanine get converted to in aminotransferase rxn?

Answer 21

pyruvate