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ARGINASE
Author(s) -
BALDWIN ERNEST
Publication year - 1936
Publication title -
biological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.993
H-Index - 165
eISSN - 1469-185X
pISSN - 1464-7931
DOI - 10.1111/j.1469-185x.1936.tb00503.x
Subject(s) - arginase , vertebrate , biology , ornithine , biochemistry , enzyme , zoology , arginine , amino acid , gene
Summary I. Arginase is a highly specific intracellular enzyme and requires that both the carboxyl and the guanidine groups shall be free if the substrate molecule is to be activated. The kinetics of arginase and its behaviour towards activators and inhibitors are very briefly discussed in the text. 2. Arginase is abundantly present in the liver of ureotelic vertebrates; small amounts are present also in the kidney and testis, but little or none elsewhere. In uricotelic vertebrates it is mainly confined to the kidney. 3. Male animals always contain about 50 per cent, more arginase than females; a sudden increase in the arginase content of the testis at puberty suggests a possible specific relation between sex and the distribution of arginase. 4. Arginase is widely distributed among invertebrates, usually in small amounts. But the terrestrial gastropods contain as much of the enzyme as do the ureotelic vertebrates. 5. The synthesis of urea by ureotelic vertebrates takes place by a cyclical mechanism involving arginase. This system is present in mammals, chelonian reptiles and Amphibia, but not in birds. It is very probably present in the elasmobranch fishes also, and the possibility that it is present in the teleosts remains open. 6. Although arginase is not concerned in the production of uric acid by uricotelic vertebrates it does account for such urea as is excreted by these forms. Its main function in the birds is that of supplying ornithine for detoxication. 7. Many invertebrates resemble the birds in possessing small amounts of arginase, which probably suffice to account for the urea which they excrete. In the terrestrial gastropods it is possible that metabolism is primarily ureotelic as in the mammals, but that urea is secondarily converted into uric acid as an adaptation to xerophilous life. 8. Although many bacteria are capable of breaking down arginine they probably contain no arginase but only guanidinodesimidase. This enzyme appears to be absent from vertebrate tissues. 9. Arginase is present early in embryonic life and is soon capable of discharging its adult function. But there exists a correlation between a high growth rate and a high content of arginase, phosphatase and nuclease, which suggests a specific association between arginase and the processes of growth.