Amylase in the hepatopancreas of an euryhaline burrowing crab: characteristics and modulation

PAGGI R.A; DE CASTRO R.E.; A. ASARO; LOPEZ MAÑANES A.A.

TURKISH JOURNAL OF ZOOLOGY

TUBITAK SCIENTIFIC & TECHNICAL RESEARCH COUNCIL TURKEY

Año: 2017 vol. 41 p. 443 - 453

1300-0179

Abstract: In spite of its inherent physiological importance, studies on the occurrence, characteristics, and modulation of amylase ineuryhaline crabs are lacking. We investigated the occurrence of amylase forms and the effect of acclimation to different salinities on theirnumber and made a partial purification and characterization of the major form present in the hepatopancreas of Neohelice granulata.Zymogram analysis revealed 5 amylase forms in crabs acclimated to 35 psu (seawater) and 37 psu, and an additional band at 10 psu,but with a major form (29 kDa) in all cases, which was partially purified and characterized. Amylolytic activity was maximal between30 and 40 °C; maintained at high NaCl concentrations (up to 4 M); increased by 5 mM K+, Li+, Co2+, and Mg (36%?45%); inhibited byCu2+, Zn2+, Cd2+, Fe2+, and Mn2+ (92.4% and 23.7%); not affected by Ni2+ or Ba2+; and enhanced almost 100% by Ca2+. Amylase exhibitedMichaelis?Menten kinetics (starch: Km = 1.24 mg mL?1; glycogen: Km = 16.19 mg mL). The potential physiological significance andrelationship to habitat conditions of the extra form in low salinity and the biochemical characteristics of the partially purified amylolyticactivity (halotolerant, differential sensitivity to ions, capability to hydrolyze starch and glycogen) are discussed. Key words: Phenotypic flexibility, amylolytic activity, digestive tract, environment, euryhaline crabs?12+