Alkaline phosphatase is homodimeric metalloenzyme which hydrolyzes the phosphomonoester into inorganic phosphate and corresponding alcohol or remove terminal monoesterified phosphate from ribo-oligonucleotide, deoxyribo-oligonucleotides, alkaloids and proteins etc.as valuable reagent. Commonly three types of alkaline phosphatase have been found in human liver, kidney, intestine, placental and bones. Serum alkaline phosphatase is markedly elevated in different types of liver and bones diseases as well as in congestive heart failure, hyperparathyroidism and intestinal diseases. Alkaline phosphatase have also been found in variety of micro-organism including E.coli, Pseudomonas, Aerobacter and Bacillus species. Alkaline phosphatase is also an important tool in molecular cloning and DNA sequencing.
Role of various types of alkaline phosphatases:
In bacteria, alkaline phosphatase is present in the periplasmic space. While in animals, its isomers are found in the he liver (isoenzyme ALP-I) and bone (isoenzyme ALP-II). There are also small amounts produced by cells lining the intestines (isoenzyme ALP-III), the placenta, and the kidney (in the proximal convoluted tubules). Where alkaline phosphatases act by splitting off phosphorus (an acidic mineral) creating an alkaline pH to residing environment. The primary importance of measuring serum alkaline phosphatase is to check the possibility of degeneration of bone (osteoporosis) and or liver (hepatobillary diseases). Thus, the serum alkaline phosphatase is a measure of the integrity of the hepatobiliary system and the flow of bile into the small intestine too. The growing children have higher level of serum alkaline phosphates than full-grown adults.
The most common alkaline phosphatases used in modern research are bacterial alkaline phosphatase from Escherichia coli and Bacillus spp.; shrimp alkaline phosphatase from Arctic shrimp (Pandalus borealis); Calf Intestinal Alkaline Phosphatase and Placental alkaline phosphatase. Another latest application of alkaline phosphatase is its use as a bio-marker/label for enzyme immunoassays and ELISA.
There are two immense uses for alkaline phosphatase in DNA modification:
1. Removal of 5' phosphates from plasmid and bacteriophage vectors by restriction enzyme. In subsequent ligation reactions, this incision prevents self-ligation to facilitate the ligation of other DNA fragments into the vector (e.g. subcloning).
2. Removal of 5' phosphates from fragments of DNA prior to labeling with radioactive phosphate
This type of dephosphorylation of DNAs was recommended with conducted 5'-recessed ends by using higher concentration of alkaline phosphatase at higher temperatures.
About Author / Additional Info:
Dr. Kirti Rani Sharma,
Assistant Professor (II),
Amity Institute of Biotechnology,
Amity University, sec-125, Gautam Buddha Nagar, Noida-201303 (UP), India.
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