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Ramos, Kristine Rose M.,Valdehuesa, Kris Niñ,o G.,Nisola, Grace M.,Lee, Won-Keun,Chung, Wook-Jin Elsevier 2018 New biotechnology Vol.40 No.2
<P><B>Abstract</B></P> <P>Research on the enzymatic breakdown of seaweed-derived agar has recently gained attention due to the progress in green technologies for marine biomass utilization. The enzymes known as agarases catalyze the cleavage of glycosidic bonds within the polysaccharide. In this study, a new β-agarase, Aga2, was identified from <I>Cellulophaga omnivescoria</I> W5C. Aga2 is one of four putative agarases from the W5C genome, and it belongs to the glycoside hydrolase 16 family. It was shown to be exclusive to the <I>Cellulophaga</I> genus. Agarase activity assays showed that Aga2 is an endolytic-type β-agarase that produces tetrameric and hexameric neoagaro-oligosaccharides, with optimum activity at 45°C and pH 8.0. Zinc ions slightly enhanced its activity while manganese ions had inhibitory effects even at very low concentrations. Aga2 has a K<SUB>m</SUB> of 2.59mgmL<SUP>−1</SUP> and V<SUB>max</SUB> of 275.48Umg<SUP>−1</SUP>. The K<SUB>cat</SUB> is 1.73×10<SUP>2</SUP> s<SUP>−1</SUP>, while the K<SUB>cat</SUB>/K<SUB>m</SUB> is 8.04×10<SUP>6</SUP> s<SUP>−1</SUP> M<SUP>−1</SUP>. Aga2 also showed good thermostability at 45°C and above, and retained >90% of its activity after repeated freeze-thaw cycles. Bioinformatic analysis of its amino acid sequence revealed that intrinsic properties of the protein (e.g. presence of certain dipeptides and the relative volume occupied by aliphatic amino acids) and tertiary structural elements (e.g. presence of salt bridges, hydrophobic interactions and H-bonding) contributed to its thermostability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Endolytic β-agarase Aga2 was identified from <I>Cellulophaga omnivescoria</I> W5C. </LI> <LI> Aga2 optimum activity was at 45°C, pH 8.0, with NA4 and NA6 as major products. </LI> <LI> Aga2 was thermostable at high temperatures as well as after many freeze-thaw cycles. </LI> <LI> Intrinsic properties and tertiary structural elements confer the thermostability. </LI> </UL> </P>
Ramos, Kristine Rose M.,Valdehuesa, Kris Niñ,o G.,Maza, Perry Ayn Mayson M.,Nisola, Grace M.,Lee, Won-Keun,Chung, Wook-Jin Elsevier Science B.V., Amsterdam. 2017 PROCESS BIOCHEMISTRY Vol.63 No.-
<P><B>Abstract</B></P> <P>An α-neoagarobiose hydrolase (α-NABH) from <I>Cellulophaga</I> sp. W5C, designated as AhgI, was identified, purified, and characterized. Its 1227 base pairs of coded sequence translate into a 408-amino acid protein that belongs to the GH117 family. Multiple sequence alignment of AhgI with other known α-NABHs showed 83% homology with AhgA from <I>Zobellia galactanivorans</I>. AhgI had an apparent molecular weight of 45kDa and was highly active at pH 7.0 and 20°C. The <I>K</I> <SUB>m</SUB> and <I>V</I> <SUB>max</SUB> values for neoagarobiose (NA2) were 1.03mM and 10.22U/mg, respectively. Apart from NA2, the enzyme showed activity against other neoagaro-oligosaccharides such as neoagarotetraose (NA4) and neoagarohexaose (NA6). AhgI was then employed in a prototype process to produce D-galactonate from <I>Gelidium amansii</I>. Agar from <I>G. amansii</I> was hydrothermally extracted and then enzymatically hydrolyzed by sequential addition of β-agarases and AhgI. The final hydrolysate containing D-galactose was then utilized for the microbial production of D-galactonate. This is believed to be the first report on the identification and characterization of an α-NABH derived from <I>Cellulophaga</I> species and its subsequent application in the synthesis of a value-added chemical directly from marine macroalgae.</P> <P><B>Highlights</B></P> <P> <UL> <LI> α-Neoagarobiose hydrolase was identified from <I>Cellulophaga</I> sp. W5C. </LI> <LI> Optimum conditions for enzyme activity are pH 7.0 and 20°C. </LI> <LI> AhgI was active towards neoagarobiose, neoagarotetraose, and neoagarohexaose. </LI> <LI> AhgI was applied for the hydrolysis of agar and subsequent D-galactonate production. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Isolation and Characterization of a Novel Marine Bacterium Belonging to Cellulophaga Genus
Kristine Rose M. RAMOS,Kris Nino G. VALDEHUESA,Perry Ayn Mayson M. MAZA,Teklebrahan Gebrekrstos WELDEM,Angelo B. BAnARES,Rhudith B. CABULONG,Grace M. NISOLA,Won Keun LEE,Wook Jin CHUNG 한국생물공학회 2016 한국생물공학회 학술대회 Vol.2016 No.10