Compositions – Water-softening or purifying or scale-inhibiting agents
Patent
1992-02-27
1994-02-15
McFarlane, Anthony
Compositions
Water-softening or purifying or scale-inhibiting agents
252DIG12, 435188, C11D 1700, C12N 996
Patent
active
052864049
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a liquid enzymatic detergent composition and to an enzymatic detergent additive in the form of a stabilized liquid for use therein. The invention also relates to a method of increasing the solubility of an enzyme, particularly in the preparation of a liquid enzymatic detergent or a liquid enzymatic detergent additive.
BACKGROUND ART
Enzymes are commonly incorporated in liquid detergents to improve detergency. The most commonly used detergent enzymes are proteases, mainly alkaline Bacillus proteases such as subtilisin Carlsberg. The prior art deals extensively with the formulation of liquid enzymatic detergents, particularly with improving the stability of the enzyme during storage. One recent example is EP 352,244.
In general, the enzyme should be fully dissolved in the liquid detergent to prevent phase separation during storage and to ensure that the enzyme activity is immediately available during washing.
We have found that in some liquid detergents, the enzyme is not fully soluble and may precipitate. It is the object of the invention to provide a liquid enzymatic detergent composition with improved enzyme solubility, an enzymatic detergent additive for use therein, and a method of improving the solubility of an enzyme without serious loss of enzyme activity.
DISCLOSURE OF INVENTION
We have, surprisingly, found that by chemical modification of free primary amino groups in an enzyme, the solubility of the enzyme can be improved while the enzyme activity is preserved. The modification preferably involves aldehyde treatment, acylation or alkylation.
It is known that aldehydes can react with primary amino groups in enzymes, and treatment of enzyme with glutaraldehyde has been widely used for immobilization of enzymes, i.e. for preparing a water insoluble enzyme product (e.g. U.S Pat. No. 3,980,521, JP-B 50-037274). It is also known from DE-A 2,919,622 that a water-insoluble product can be obtained by treatment of a protease with a polysaccharide derivative containing aldehyde groups such as dialdehyde starch. Further, it is known from J. Boudrant et al., Biotech. and Bioeng., XVIII, 1719-34 (1976) that aldehyde treatment of a typical detergent enzyme converts part of the enzyme protein into an insoluble fraction. GB 1,280,497 discloses treatment of enzyme with e.g. glutaraldehyde and removal of insoluble residue to improve the stability of the enzyme when added to a solution of powder detergent. There is, however, no suggestion in the prior art that such treatment of an enzyme can be used to increase its solubility.
Accordingly, the invention provides a liquid enzymatic detergent composition and an enzymatic detergent additive in the form of a stabilized liquid, each characterized by comprising dissolved therein an enzyme containing chemically modified primary amino groups.
Further, the invention provides a method of increasing the solubility of an enzyme containing free primary amino groups, said method comprising chemical modification of part or all of said primary amino groups.
DETAILED DESCRIPTION OF INVENTION
Enzyme
Besides the terminal amino group, most enzymes, in particular most detergent enzymes, contain lysine with free primary amino (--NH.sub.2) groups. The invention may be used for modifying any enzyme, provided it contains free primary amino groups, preferably at least 2, and most preferably at least 4 free primary amino groups per molecule. The enzyme typically has molecular weight 20,000-100,000, especially 20,000-60,000, and isoelectric point 7-12. The enzyme may be a protease, an amylase, a lipase, a peroxidase or a cellulase, especially a subtilisin (an alkaline Bacillus protease), e.g. Subtilisin Carlsberg, derived from B. licheniformis (e.g. Alcalase.RTM., product of Novo Nordisk A/S), Savinase.RTM. (product of Novo Nordisk, produced from alkalophilic Bacillus according to U.S. Pat. No. 3,723,250) or a mutant subtilisin such as those described in WO 89/06279 or DK 0541/90. Subtilisin Carlsberg has molecular weight 27,000, pl around 8
Eriksen Nina
Pedersen Gitte
Lambiris Elias J.
McFarlane Anthony
Novo Nordisk A S
Phan Nhat D.
Zelson Steve T.
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