Functional changes of dextran-modified alkaline proteinase from alkalophilic Bacillus sp.
A serine alkaline proteinase (EC 3.4.21.62) from Bacillus sp. (ALPase I) was modified with the 2,4-dialdehyde derivative of clinical dextran (dialdehyde dextran). The modified preparation was purified using an ion-exchange column and gel filtration. The modified enzyme contained 75% carbohydrate by weight. The isoelectric point (pI) of ALPase I was converted from 8.2 to approximately 5.0 by this modification. The specific activity of the dextran-modified ALPase I was 56% of that of the native enzyme when milk casein was used as a substrate. It also had some superior characteristics: the thermostability of the modified enzyme at pH 10.0 was about 10-15 degrees C higher than that of control. In organic solvents such as n-hexane, benzene, and toluene, the hydrolysis reaction of the modified ALPase I for the fluorogenic substrate, succinyl-L-alanyl-L-alanyl-L-prolyl-L-phenylalanyl-4-methylcoumaryl-7-am ide (Suc-Ala-Ala-Pro-Phe-MCA), was several times higher than that of the native. This modification greatly improved the stability of ALPase I against nonionic and anionic surfactants. After exposure to lauryl benzene sulfonate and sodium lauryl sulfonate the modified enzyme retained over 95 and 90% of its activity, respectively, but the native enzyme lost its activity. We conclude that modification of serine proteinases with dialdehyde-dextran might be a useful method for improving enzyme character for enzyme technology.
Yamagata
Y
Y
Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai, Japan.
Arakawa
K
K
Yamaguchi
M
M
Kobayashi
M
M
Ichishima
E
E
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003911:Dextrans; D004795:Enzyme Stability; D007525:Isoelectric Focusing; D007700:Kinetics; D008969:Molecular Sequence Data; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D013816:Thermodynamics
D003911:Dextrans; C026948:dextran dialdehyde; D012697:Serine Endopeptidases