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Purification and Characterization of an Oligo‐1,6‐glucosidase from the Caldoactive Thermophile Bacillus caldotenax
Author(s) -
Suzuki Y.,
Sugita N.,
Kishimoto T.
Publication year - 1997
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19970490406
Subject(s) - thermostability , enzyme , sedimentation coefficient , isoelectric point , chemistry , stokes radius , biochemistry , thermophile , chromatography , molecular mass
An oligo‐1,6‐glucosidase (dextrin 6‐α‐ D ‐glucanhydrolase, EC 3.2.1.10) of the caldoactive thermophile Bacillus caldotenax KP 1213 (YT‐G, DSM406) was purified to homogeneity. Its relative molecular weight, Stokes radius, sedimentation coefficient at 20°C in water, molar absorption coefficient at 280nm and pH 6.8, and isoelectric point were estimated to be 64,000, 3.3nm, 4.8S, 122,000 M −1 cm −1 , and 4.9, respectively. The enzyme N‐terminal sequence of twenty residues was determined to be Met 1 ‐Glu‐Trp‐Ala‐Trp‐Lys‐Glu‐Ala‐Val‐Val‐Tyr‐Gln‐Ile‐Tyr‐Pro‐Arg‐Met‐Phe‐Tyr 20 . The enzyme shared its antigenic groups in part with the homologue from Bacillus thermoglucosidasius KP1006 (DSM2542, obligate thermophile). The B. caldotenax enzyme was most active at 70°C and at pH 6.0–6.8. The best substrate for the enzyme was isomaltotriose of naturally‐occurring oligo‐ and polysaccharides tested. The enzyme half‐life at pH 6.8 was 10min at 75°C. The enzyme (Pro, 5.93mol%) fairly matched with a positive relationship between the thermostability of its six bacillary counterparts and their proline mol% contents. This relationship has been found to hold for sixteen bacterial enzymes from other four different groups (α‐glucosidases, pullulanases and 3‐isopropylmalate dehydrogenases).