Lecture 8

Question 1

Amino acid plasma level

Answer 1

4-8 ml / dl

Question 2

Sources of amino acids

Answer 2

1. Dietry protein
2. Non-essential proteins
3. Breakdown of tissue protein

Question 3

Fate of amino acids

Answer 3

1. Functional proteins
2. Structural proteins
3. Small peptides e.g. Glutathione)
4. Non-protein nitrogenous compounds
5. Breakdown → x-kelo acid , ammonia

Question 4

What’s the definition of transamination?

Answer 4

Transfer of amino group from alpha amino acid to alpha keto acid forming new alpha
Amino acid and newalpha keto acid

Question 5

Site of transamination?

Answer 5

Liver
( nb: transaminatio, decarboxylation in liver only BUT
Diminution is in river and kidney)

Question 6

Enzymes of transamination

Answer 6

Transaminases eg. GPT (ALT) & GOT (AST)

Question 7

Coenzyme of transamination (and AA metabolic reactions)

Answer 7

Pyridoxal phosphate:
Intermediate carrier of amino group → pyridoxine → gives amino group to alpha keto acid

Question 8

All amino acids can be transaminated except?

Answer 8

Lysine, threonine (not reversible and transamination should be reversible)
Proline, hydroxyproline

Question 9

What is the reaction ALT (GPT)

Answer 9

Amino group from Glutamic ( AA) to Pyruvic → Alanine + alpha ketoglutamic

Question 10

Site of GPT (ALT)

Answer 10

Cytoplasm of LIVER (only)

Question 11

Reaction of AST (GOT)

Answer 11

Amino group from glutamic (AA) to OAA → Aspartic acid + alpha ketoglutaric acid

Question 12

Site of AST (GOT)

Answer 12

Cytoplasm and mitochondria of LIVER and HEART…

Question 13

Explain clinical significance of transaminases?

Answer 13

Liver dse → both ALT and AST
Acute liver dse → ALT (GPT) more
Chronic liver dse → AST (GOT) more
Herat dse → GOT only

Question 14

Define deamination?

Answer 14

Removal of amino group from alpha amino acid to form alpha keto acid

Question 15

Site of deamination?

Answer 15

Liver and kidney
NB. Transamination, Decarboxylation → liver
Deamination → liver AND kidney

Question 16

Types of deamination

Answer 16

• NON-OXIDATIVE
  -OXIDATIVE :
  1. L-amino acid oxidase
  2. D-amino acid oxidase
  3. Glutamate dehydrogenase :
  
  • for glutamic acid
  • anaerobic type
  • NAD & NADP coenzymes
  • widely distributed

Question 17

Define amino acid decarboxylation

Answer 17

Removal of carboxylic acid in form of CO2 forming amines ( in liver)

Question 18

Enzymes of AA Decarboxylation?

Answer 18

Decarboxylases and pyridoxal phosphate (PLP) coenzyme

Question 19

Examples of AA decarboxylation?

Answer 19

Histidine → Histamine (vasodilation and increase HCl)
Glutamic acid → GABA (inhibitory chemical transmitter in brain)
NB. PLP (pyridoxal) dificiency in brain inhibits GABA leading to convulsion