7. Simple, Hydroxy And Sulphur Containing Amino Acid Flashcards
Special products of Glycine?
Glycine may be used for the biosynthesis of the following compounds (Fig. 15.4):
i. Creatine, creatine phosphate and creatinine
ii. Heme
iii. Purine nucleotides
iv. Glutathione
v. Conjugating agent
vi. Neurotransmitter
vii. Proteins
viii. Serine
ix. Glucogenic pathway
For details refer text pg 184 185
Explain Hyperoxaluria?
Primary Hyperoxaluria
i. Increasedexcretionofoxalatesisobserved(upto600 mg/day, compared to a normal of 50 mg/day). The oxaluria is due to increased production of oxalates. It is an autosomal recessive trait.
ii. The disease is due to a protein targetting defect. Normally, the enzyme alanine glyoxalate amino transferase (No.1 in Fig. 15.7) is located in peroxi- somes; but in these patients the enzyme is present in mitochondria (see also Box 41.1). So, enzyme is inactive.
iii. This leads to increased pool size of glyoxalate, and excess production of oxalate. Renal deposition of oxalates would cause nephrolithiasis, renal colic and hematuria. Extrarenal oxalosis may be seen in heart, blood vessels, bone, etc.
iv. Type 2 primary hyperoxaluria is a milder condition causing only urolithiasis and results from deficient activity of cytoplasmic glyoxalate reductase
Explain Cystinuria?
Cystinuria is one of the inborn errors of metabolism included in the Garrod’s tetrad. It is an autosomal recessive condition.
The disorder is attributed to the deficiency in transport of amino acids Signs and symptoms include:
i. Abnormal excretion of cystine and to a lesser extent lysine, ornithine and arginine. Hence the condition is also called Cystine-lysinuria.
ii. Crystalluria. In acidic pH, cystine crystals are formed in urine.
iii. The crystals form calculi (stones).
iv. Obstructive uropathy which may lead to renal
insufficiency.
v. Treatment is to increase urinary volume by
increasing fluid intake. Solubility of cystine is increased by alkalinization of urine by giving sodium bicarbonate.
