Ans. d (L-Phenylalanine) (Ref. Biochemistry by Vasudevan, 4th ed., 57; 5th ed., 55-56)ALKALINE PHOSPHATASE# The pH optimum for the enzyme reaction is between 9 and 10.# It is activated by magnesium and manganese.# Zinc is a constituent ion of ALR# It is produced by osteoblasts of bone, and is associated with the calcification process.# It is localised in cell membranes (ecto-enzyme), and is associated with transport mechanisms in liver, kidney and intestinal mucosa.# For estimation, sodium phenyl phosphate is used as the substrate, pH is adjusted to 9.9, serum sample is added as the source of ALP and incubated.# Normal serum value of ALP is 40-125 U/L.# Raised Levels:Mild increasepregnancy.Moderate (2-3 times) increaseIn infective hepatitis, alcoholic hepatitis or hepatocellular carcinoma, Hodgkin's lymphoma, congestive cardiac failure or ulcerative colitis.Very high levels of ALP (10-12 times)In extrahepatic obstruction (obstructive jaundice) or cholestasis.Drastically high levels of ALP (10-25 times)Bone diseases where osteoblastic activity is enhanced such as Paget's disease, rickets, osteomalacia, osteoblastoma, metastatic carcinoma of bone, and hyperparathyroidism.Iso-enzymes of Alkaline Phosphatase# Alpha-1 ALP moves in alpha-1 position, it is synthesized by epithelial cells of biliary canaliculi. It is about 10% of total activity and is increased in obstructive jaundice and to some extent in metastatic carcinoma of liver.# Alpha-2 heat labile ALP is stable at 56degC; but loses its activity when kept at 65degC for 30 minutes. It is produced by hepatic cells. Therefore, exaggerated alpha-2 band suggests hepatitis. This liver iso-enzyme forms about 25% of total ALP.# Alpha-2 heat stable ALP will not be destroyed at 65degC, but is inhibited by phenylalanine. It is of placental origin, which is found in blood in normal pregnancy. An iso-enzyme closely resembling the placental form is characteristically seen in circulation in about 15% cases of carcinoma of lung, liver and gut and named as Regan iso-enzyme (after the first patient in whom it was detected) or carcinoplacental iso-enzyme. Chronic heavy smoking also increases Regan iso-enzyme level in blood. Normal level is only 1% of the total ALP.# Pre-beta ALP is of bone origin and elevated levels are seen in bone diseases. This is most heat labile (destroyed at 56degC, 10 min). Wheat germ lectin will precipitate bone isoenzyme. This constitutes about 50% of normal ALP activity.# Gamma-ALP is inhibited by phenylalanine and originates from intestinal cells. It is increased in ulcerative colitis. About 10% of plasma ALP are of intestinal variety.# Leucocyte alkaline phosphatase (LAP) is significantly decreased in chronic myeloid leukemia. It is increased in lymphomas and leukemoid reactions.ALANINE AMINO TRANSFERASE (ALT)# It is also called as serum glutamate pyruvate transaminase (SGPT).# The enzyme needs pyridoxal phosphate as co-enzyme.# Normal serum level of AL T for male is 13^4-0 U/L and for female is 10-28 U/L.# Very high values (100 to 1000 U/L) are seen in acute hepatitis, either toxic or viral in origin.# Both ALT and AST levels are increased in liver disease, but ALT > AST.# Moderate increase (25 to 100 U/L) may be seen in chronic liver diseases such as cirrhosis, Hepatoma.# A sudden fall in ALT level in cases of hepatitis is very bad prognostic sign.NUCLEOTIDE PHOSPHATASE# It is also known as 5' nucleotidase.# It is a marker enzyme for plasma membranes and is seen as an ecto-enzyme (enzyme present on the cell membrane).# Serum samples contain both ALP and NTP.# These are distinguished by Nickel ions which inhibit NTP but not ALP.- Normal NTP level in serum is 2-10 IU/L. It is moderately increased in hepatitis and highly elevated in biliary obstruction.# Unlike ALP, the level is unrelated with osteoblastic activity and therefore unaffected by bone disease.GAMMA GLUTAMYL TRANSFERASE (GGT)# The old name was gamma glutamyl transpeptidase.# It can transfer gamma glutamyl residues to substrate.# In the body it is used in the synthesis of glutathione.# It is seen in liver, kidney, pancreas, intestinal cells and prostate gland.