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

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

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 semitrivial ...

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

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

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 (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar is ...

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

Carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

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.

References

External links

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

Function in Environment

See also

References

External links