title: Intracellular alginolytic enzymes of the marine bacterium Pseudoalteromonas citrea KMM 3297.
abstract: The marine bacterium Pseudoalteromonas citrea KMM 3297 is an associate of the holothurian Apostichopus japonicus. When grown in a medium containing glucose, the strain produces two intracellular alginolytic enzymes, AlI and AlII. Fucoidan from the brown alga Fucus evanescens induces synthesis of one more alginolytic enzyme, AlIII. These enzymes were separated using anion-exchange chromatography. The alginate lyase AlI completely retains its activity at 35 degrees C, AlII and AlIII being stable at 45 degrees C. The alginate lyases exhibit maximal activities in the range of pH 7-8. The molecular weights of AlI, AlII, and AlIII determined by gel filtration are 25, 79, and 61 kD, respectively. All the investigated enzymes are endo-type alginate lyases. They catalyze degradation of polyguluronate (poly-G) and polymannuronate (poly-M) yielding oligosaccharides of the polymerization degree of 5 > or = n > or = 3 with the unsaturated bond between the C4 and C5 atoms of the non-reducing terminus. A mixture of these three enzymes exhibits synergism while acting on the polymeric substrate. The Km values of the alginate lyase AlI for poly-G and poly-M are 24 and 34 micro g/ml, respectively. Alginate lyase AlIII exhibits less affinity to poly-M (Km = 130.0 microg/ml) than to poly-G (Km = 40.0 microg/ml). NaCl (0.2 M), MgCl2 and MgSO4 (0.01 M) activate all three enzymes more than twofold. The presence of several alginolytic enzymes of different specificity provides efficient destruction of alginic acids of brown algae by the strain P. citrea KMM 3297.
authors.affiliation: Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690022, Russia.
authors.forename: S A
authors.initials: SA
authors.lastname: Alekseeva
authors.forename: I Yu
authors.initials: IY
authors.lastname: Bakunina
authors.forename: O I
authors.initials: OI
authors.lastname: Nedashkovskaya
authors.forename: V V
authors.initials: VV
authors.lastname: Isakov
authors.forename: V V
authors.initials: VV
authors.lastname: Mikhailov
authors.forename: T N
authors.initials: TN
authors.lastname: Zvyagintseva
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D002852:Chromatography, Ion Exchange; D020723:Glucuronic Acid / Q000737:chemistry*; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D006603:Hexuronic Acids / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008190:Lyases / Q000737:chemistry* / Q000302:isolation & purification; D008670:Metals / Q000737:chemistry; D008970:Molecular Weight; D000459:Phaeophyceae / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012616:Sea Cucumbers / Q000382:microbiology; D013379:Substrate Specificity
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D008670:Metals; D011134:Polysaccharides; D011135:Polysaccharides, Bacterial; C111091:polyguluronic acid; C437391:polymannuronic sulfate; D020723:Glucuronic Acid; C007789:fucoidan; D008190:Lyases