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In bacteria, alkaline phosphatase is found in the periplasmic space, external to the cell membrane. Since this space is much more subject to environmental variation than the actual interior of the cell, bacterial alkaline phosphatase is comparatively resistant to inactivation, denaturation, and degradation, and also has a higher rate of activity. Although the actual purpose of the enzyme is still not fully understood, the simple hypothesis, that it is a means for the bacteria to generate free phosphate groups for uptake and use, is supported by the fact that alkaline phosphatase is usually only produced by the bacteria during phosphate starvation and not when phosphate is plentiful. However, other possibilities exist; for instance, the presence of phosphate groups usually prevents organic molecules from passing through the membrane, therefore dephosphorylating them may be important for bacterial uptake of organic compounds in the wild. Some complexities of bacterial regulation and metabolismMetabolism in the most general sense, is the ingestion and breakdown of complex compounds, coupled with the liberation of energy, and the consequent generation of waste products. It is major process of living organisms, and because this process can happen suggest that other, more subtle, purposes for the enzyme may also play a role for the cell. In the laboratoryBiochemistry laboratory at the University of Cologne. A laboratory (often abbreviated lab is a place where scientific research and experiments are conducted. The equipment in a laboratory will depend on what the lab is used for. Chemistry and biochemistry, however, mutantThis article is about the real-world biological phenomenon of mutants; to see fictional mutants see Mutant (fictional A mutant is an individual, organism, or new genetic character arising or resulting from an instance of mutation, which is a sudden struct Escherichia coliEscherichia coli (usually abbreviated to E. coli is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. Its presence in groundwater lacking alkaline phosphatase survive quite well, as do mutants unable to shut off alkaline phosphatase production.
In humans, alkaline phosphatase is present in all tissues throughout the entire body, but is particularly concentrated in the liverThe liver is an organ in vertebrates including humans. It plays a major role in metabolism and has a number of functions in the body including detoxification, glycogen storage and plasma protein synthesis. It also produces bile which is important for dige, bile ductA bile duct is any of a number of long tube-like structures that carry bile. Bile, required for the digestion of food, is excreted by the liver into passages that carry bile toward the hepatic duct, which joins with the cystic duct (carrying bile to and f, bileBile (or gall is a bitter, greenish-yellow alkaline fluid secreted by the liver of many vertebrates. It is stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion. Bile salts act to so, boneFor other uses of the word "bone", see bone (disambiguation). Gray's illustration of a human femur, a typically recognized bone. Bone refers either to a hardened connective tissue or to one of the individual structures, or organs, into which it is formed,, and the placenta.
The most common alkaline phosphatases used in research are:
Improper blood plasma (serum) levels of ALP for a person's particular age and gender are typically indicative of a fractured bone or more serious disease, such as cancer.
Alkaline phosphatase has become a useful tool in molecular biology laboratories, since DNA normally possesses phosphate groups on the 5' end. Removing these phosphates prevents the DNA from ligating (the 5' end attaching to the 3' end), thereby stabilizing the DNA until the next step of the process for which it is being prepared; also, removal of the phosphate groups allows radiolabeling (replacement by radioactive phosphate groups) in order to measure the presence of the labeled DNA through further steps in the process or experiment. For these purposes, the calf intestine alkaline phosphatase is the most useful, as it is the easiest to inactivate once it has done its job.