Enzymatic properties and primary structures of two α-amylase isozymes from the Pacific abalone Haliotis discus hannai

Abstract

Two -amylase (EC 3.2.1.1) isozymes, HdAmy58 and HdAmy82, with approximate molecular masses of 58 kDa and 82 kDa, respectively, were isolated from the digestive fluid of the pacific abalone Haliotis discus hannai. Optimal temperatures and pHs for HdAmy58 and HdAmy82 were at 30 o C and 6.7, and 30 o C and 6.1, respectively. Both enzymes similarly degraded starch, glycogen, and maltooligosaccharides larger than maltotriose producing maltose and maltotriose as the major degradation products. However, the activity toward maltotetraose was appreciably higher in HdAmy82 than HdAmy58. cDNAs encoding HdAmy58 and HdAmy82 were cloned and the amino-acid sequences of 511 and 694 residues for HdAmy58 and HdAmy82, respectively, were deduced. The putative catalytic domains of HdAmy58 and HdAmy82 were located in the 17-511 th and 19-500 th amino-acid regions, respectively, and they showed approximately 50% amino-acid identity to each other. These sequences also showed 62 -99% amino-acid identity to the catalytic domains of known -amylases that belong to glycoside-hydrolase-family 13. The difference in the molecular masses between HdAmy58 and HdAmy82 was ascribed to the extension of approximately 190 residues in the C-terminus of HdAmy82. This extended region showed 41 -63% amino-acid identity with the ancillary domains of several -amylases previously reported.

Comprehensive enzymatic analysis of the amylolytic system in the digestive fluid of the sea hare, Aplysia kurodai: Unique properties of two α‐amylases and two α‐glucosidases

“…2 A, both amylases yielded single protein bands corresponding to molecular masses of 59 kDa and 80 kDa, respectively. Recently, 58‐kDa (HdAmy58) and 82‐kDa amylases (HdAmy82) were purified from the digestive fluid of Pacific abalone [9]. The two amylases from both species were purified by similar procedures, including hydrophobic, anionic ion‐exchange, and hydroxyapatite column chromatography.…”

Characterization of a GHF45 cellulase, AkEG21, from the common sea hare Aplysia kurodai

“…Herbivorous mollusks produce various kinds of polysaccharide-degrading enzymes, e.g., alginate lyase (Wong et al, 2000; Shimizu et al, 2003; Suzuki et al, 2006; Rahman et al, 2010), mannanase (Zahura et al, 2010, 2011), laminarinase (Kozhemyako et al, 2004; Kovalchuk et al, 2006, 2009; Kumagai and Ojima, 2009, 2010; Pauchet et al, 2009), amylase (Kumagai et al, 2012) and cellulase (Suzuki et al, 2003; Guo et al, 2008; Sakamoto and Toyohara, 2009). Among these enzymes, cellulase appears to be most widely distributed in mollusks (Elyakova, 1972; Nishida et al, 2007; Sakamoto and Toyohara, 2009; Ravindran et al, 2010; Nagano et al, 2011).…”

Isolation and production of thermostable α-amylase from thermophilic Anoxybacillus sp. KP1 from Diyadin hot spring in Ağri, Turkey

“…α-Amylase (EC 3.2.1.1) is an enzyme that hydrolyses internal α-1,4-glycoside linkages of α-glucans, such as starch and glycogen (Kumagai et al 2013). Amylases are used in filling of pores of texture and papers, desizing of starch in woven texture in textile, in removing food and starch stains in dry cleaning, in food biotechnology in the following applications: bakery, liquefying doughs, production of starch hydrolysis products such as glucose and fructose, production of corn and chocolate syrup, production of low-calories beer, in purification of apple and pear juice, malt production, in removing stickiness in paper industry, in detergent industry as well as in medical industry (Gupta et al 2003;Ul-Haq et al 2003;Apar &Özbek 2004).…”