Octopine
- Na -(1- carboxyethyl) arginine
- N2 - (D-1 -carboxyethyl) -L-arginine
- 2 - (1 -carboxy -ethylamino )-5 -guanidino - pentanoic acid
- 2 - (1 -carboxy -ethylamino )-5- guanidino valeric acid
White to brownish solid
283-284 ° C
Template: Infobox chemical / molecular formula search available
D- octopine is a guanidine derivative. It was different from muscle tissue invertebrates, such as nudus isolated eg Octopus, Pecten maximus or Sipunculus where there is a functional analogue of the lactic acid (lactate ).
History
Octopine is the first isolated Opin. It owes its name Octopus octopodia, from which it was obtained in 1927.
Biosynthesis
D- octopine is formed by a stereoselective NADH-dependent octopine dehydrogenase (EC 1.5.1.11 ) from pyruvate and L- arginine via a reductive condensation. L- arginine itself, is recovered from phospho -L- arginine. This can be reoxidized obtained in the reduced nicotinamide adenine dinucleotide NADH glycolysis, so that NAD is produced. This corresponds to the lactic acid fermentation is reduced in the pyruvate to L- lactate.
The reaction is also reversible: From NAD can again NADH formed and D- octopine be cleaved into pyruvate and L- arginine.
Importance
Squid must be able to move quickly escape or attack, which requires a lot of energy in the form of ATP. However, the necessary ATP can not be recovered from the aerobic respiration, because oxygen can not pass into the cells fast enough. Squid in a specific muscle is responsible for the rapid movement, which relates energy to anaerobic glycolysis pathways through the formation of D- octopine.
It has been anticipated for a long time that, in contrast to the lactic acid fermentation, accumulating D- octopine as a weak acid does not contribute to acidification of the cell ( acidosis). It seems, however, that D- octopine in contrast to lactate the intracellular space can not leave and thus accumulates in larger amounts. Finally, the biochemical formation of D - octopine would also lead to acidosis.