Agarase (, ''AgaA'', ''AgaB'', ''endo-β-agarase'', ''agarose 3-glycanohydrolase'') is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

with

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

''agarose 4-glycanohydrolase''. It is found in agarolytic

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

and is the first enzyme in the

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...

catabolic pathway. It is responsible for allowing them to use agar as their primary source of

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

and enables their ability to thrive in the ocean. Agarases are classified as either α-agarases or β-agarases based upon whether they degrade α or β linkages in agarose, breaking them into oligosaccharides. When secreted, α-agarases yield oligosaccharides with 3.6 anhydro-L-galactose at the reducing end whereas β-agarases result in D-galactose residues.

Function in Environment

As could be expected, many species of agar-degraders are marine micro-organisms – an adaptation to their environment which would be wasted in the majority of micro-organisms existing on land (although there are such examples, including a species of ''Paenibacillus'' in the Rhizosphere of Spinach). From species within genus ''Vibrio'' to ''Alteromonas'', the presence of agarase allows agar-degrading bacteria an abundant food source in the ocean. Research also demonstrates that glucose can inhibit extracellular agarase secretion (but not transcription), causing it to degrade within the cell and thus limit growth of the bacteria. In addition, a study of the effects of phosphate limitation on agarase shows that limiting phosphate increases both intracellular agarase production and extracellular secretion, whereas a magnesium limitation does not. This further highlights the niche which this class of bacteria usually occupies, as the concentration of glucose or phosphate in the ocean is very low while magnesium concentration is generally much higher, suiting the agar-degrading bacteria’s agarase production; there is simply no need to use glucose in the ocean, so many organisms don't. While the optimal pH of agarase is 5.5, it is stable at a tolerant range, from 4.0 to 9.0.

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* {{Portal bar, Biology, border=no EC 3.2.1

Function in Environment

See also

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External links