Physicochemical characteristics of a thermostable gellan lyase from Geobacillus stearothermophilus 98.
A purified thermostable gellan lyase, produced by a thermophilic bacterium, Geobacillus stearothermophilus 98, was characterized in relation to its physicochemical properties. The gellan lyase was established to have a molecular weight of 216 kDa, defined by capillary gel electrophoresis. Amino acid analysis revealed high quantities of Lys, His, Ala, Val, Ile, Glx, and Pro residues. The circular dichroism revealed 45% beta-structure and practically lack of a-spiral domains. Kinetic studies showed high affinity of the enzyme to gellan as a substrate (Km = 0.21 microM). The thermal denaturation investigated by cicular dichroism showed a highly cooperative transition with a midpoint (Tm) at about 75 degrees C. A single product was identified after enzyme action on gellan. Large exothermic aggregation near Tm was observed by differential scanning calorimetry. Two types of gellan lyase crystals were reproducibly isolated.
Derekova
Anna
A
Department of Extremophilic Bacteria, Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., bl. 26, Sofia 1113, Bulgaria.
Atanassova
Miroslava
M
Christova
Petya
P
Tchorbanov
Bojidar
B
Shosheva
Alexandra
A
Mandeva
Rossitsa
R
Rodríguez-Alonso
Patricia
P
Garabal
Jose I
JI
Kambourova
Margarita
M
D000596:Amino Acids / Q000032:analysis; D001407:Bacillus / Q000201:enzymology*; D002855:Chromatography, Thin Layer; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D007700:Kinetics; D011133:Polysaccharide-Lyases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013816:Thermodynamics
D000596:Amino Acids; D011133:Polysaccharide-Lyases; C091406:gellan lyase