Partial characterization of chitin degrading enzymes from two euphausiids, Euphausia superba and Meganyctiphanes norvegica

Abstract

Summary. Chitinase and N-acetyl-~-D-glucosaminidasehave been demonstrated in Meganyctiphanes norvegica and in Euphausia superba and partly characterized. The enzymes from both species have broad pH-optima (maxima around pH 5.0) and temperature optima between 40 and 50°C. The enzymes are relatively stable; even at about 45 °C half of the enzyme activity is retained after 30 min incubation. The presence of fluoride does not affect enzymatic activity. Chitinase activity appears in three different molecular masses, N-acetyl-[~-D-glucosaminidases in two different forms, pH and temperature optima, thermal stability and kinetic properties of the two enzymes are strikingly similar in the polar E. superba versus the boreal euphausiid M. norvegica. Enzyme activity in the lower temperature range is still high, whereas activation energies are low in both euphausiids. This suggests a functional adaptation to a low temperature range in seawater.

Physiology and Metabolism of Northern Krill (Meganyctiphanes norvegica Sars)

“…Studies on the properties of digestive enzymes were primarily focused on chitinolytic and proteolytic enzymes. Spindler and Buchholz (1988) identified, in the extracts of whole animals, different forms of endo-and exochitinases with broad pH optima and high stabilities. Separate analyses of the digestive organs and the cuticle revealed the presence of specific chitinases which are involved either in moulting or in digestion (Peters et al, 1998(Peters et al, , 1999.…”

“…Laboratory experiments showed that these bacteria seem to contribute to a lesser extent to the production of a range of enzymes, including chitinolytic and proteolytic Proteolytic enzymes Total proteinase (alk.) Azocasein Spindler and Buchholz (1988), Buchholz (1989), Donachie et al (1995), Kreibich et al (2010), Kreibich (unpublished), Saborowski (unpublished) Trypsin BAPNA, TAME Båmstedt (1988), Dittrich (1992a,b), Kreibich et al (2010), Kreibich (unpublished), Saborowski (unpublished Fevolden (1982), Donachie et al (1995) Valine arylamidase L-Yalyl-2-naphthylamide Donachie et al (1995) Cysteine arylamiadse L-Cystyl-2-naphtylamide Donachie et al (1995) Esterases and lipases Esterase (C2) 1-Naphthyl acetate Fevolden (1982) …”

“…Spindler and Buchholz (1988), Buchholz (1989), Donachie et al (1995) enzymes. However, none of the enzymes studied in the digestive organs of krill were exclusively of bacterial origin.…”

“…Moulting: Spindler and Buchholz (1988) examined the potential adaptive properties of biocatalysts in the chitinolytic enzymes of M. norvegica and E. superba. In both species, the authors found similar temperature optima around 40-50 C. Although enzyme activity was still high at 0 C. In both euphausiids, activation energies were reduced at lower temperatures.…”

A soluble, dye-labelled chitin derivative adapted for the assay of krill chitinase

“…Chitinase activity by end-product detection was determined reductimetrically according to Boden et al (1985) as modified by Spindler and Buchholz (1988) using purified crustacean chitin.…”