Partial characterisation of digestive proteases of the Mayan cichlid Cichlasoma urophthalmus

Abstract

The characterisation of digestive proteases in native freshwater fish such as the Mayan cichlid Cichlasoma urophthalmus provides scientific elements that may be used to design balanced feed that matches with the digestive capacity of the fish. The purpose of this study was to characterise the digestive proteases, including the effect of the pH and the temperature on enzyme activity and stability, as well as the effect of inhibitors using multienzymatic extracts of the stomach and intestine of C. urophthalmus juveniles. Results showed that the optimum activities of the acid and alkaline proteases occurred at pH values of 3 and 9, respectively, whereas their optimum temperatures were 55 and 65 °C, respectively. The acid proteases were most stable at pH values of 2–3 and at temperatures of 35–45 °C, whereas the alkaline proteases were most stable at pH values of 6–9 and at 25–55 °C. The inhibition assays recorded a residual activity of 4% with pepstatin A for the acid proteases. The inhibition of the alkaline proteases was greater than 80% with TPCK, TLCK, EDTA and ovalbumin, and of 60 and 43.8% with PMSF and SBT1, respectively. The results obtained in this study make it possible to state that C. urophthalmus has a sufficiently complete digestive enzyme machinery to degrade food items characteristic of an omnivorous fish species, although specimens showed a tendency to carnivory.

Partial characterization of digestive proteases of the three-spot cichlidCichlasoma trimaculatum(Günter 1867)

“…; Cuenca‐Soria et al . ). Considering the above, the specificity of the pH values and the high tolerance to pH changes of the digestive proteases (stomach and intestine) indicate that the catalytic centres in the molecules are properly arranged with an adequate ionic conformation to undergo catalysis effectively (Álvarez‐González ).…”

Study on enzymes of industrial interest in digestive viscera: Greater amberjack (Seriola dumerili)

“…Cuenca-Soria et al [22] observed the chymotrypsin activity of 0.52 and 0.8 IU/mg for the Mayan cichlid Cichlasoma urophthalmus. Zhou et al [23] reported that chymotrypsin of marine fish that acclimated to cold regions has higher catalytic activities and S. dumerili is a species that acclimated to cold water.…”

“…When subjected to a potent serine protease inhibitor (PMSF), activity of 62.18% was detected for trypsin of S. dumerili. Cuenca-Soria et al [22] reported a high degree of inhibition on alkaline proteases (trypsin and chymotrypsin) from extracts of C. urophthalmus by specific inhibitors such as TPCK, TLCK, and EDTA (greater than 80%) and PMSF (60%). When using the specific inhibitor of chymotrypsin (TPCK), residual trypsin activity of 54.03% was detected for S. dumerili.…”

Lipid requirement using different oil sources in Mayan cichlid Cichlasoma urophthalmus larvae (Percoidei: Cichlidae)

“…The acid protease (pepsin) is secreted by the stomach and promotes the acceleration of digestion processes, which increases the hydrolysis of proteins, helping the alkaline digestive proteases, located in the intestine, release short peptides and amino acids for their absorption by the enterocytes. It should be noted that larvae of C. urophthalmus present a digestion of alkaline proteases from yolkabsorption (López-Ramírez et al, 2011), and at day 9 after the hatching, the stomach appears, thus enhancing its protein hydrolysis capacity (Cuenca-Soria et al, 2014), which indicates that its digestive system is fully developed.…”