ENHANCERS SUCH AS N-HYDROXYACETANILIDE
FIELD OF INVENTION
The invention relates to a very effective method of bleaching a dye with a laccase enzyme and an enhancing agent. The invention also relates to a detergent composition.
BACKGROUND ART
It has earlier been found that coloured substances leached from dyed fabrics could be bleached by means of a phenol oxidizing enzyme. The use of peroxidases or oxidases for inhibiting dye transfer in this way is described in WO 91/05839. It has also been shown that certain oxidizable substances, described as accelerators, enhancing agents or mediators, e.g., metal ions; phenolic compounds such as 7-hydroxycoumarin, vanillin, and p-hydroxybenzenesulfonate, are able to enhance the enzymatic bleaching reactions (see WO 91/05839).
Other types of enhancing agents have also been disclosed, e.g., phenothiazines, phenoxazines, methylsyringate and acetosyringone (see WO 94/12621, WO 95/01426 and WO 95/01426).
Yet another type of enhancing agents are the aliphatic, cycloaliphatic, heterocyclic and aromatic compounds containg NO, NOH or H-N(R)-OH disclosed in WO 94/29425 and WO 97/48786. In WO 94/2 94 25 and WO 97/4 8786 benzotriazoles are preferred as enhancing agents for bleaching dyes.
It is the object of this invention to provide a selected group of -NOH compounds which, together with laccases, are very effective for bleaching dyes in solution.

SUMMARY OP THE INVENTION
It has now surprisingly been found that a selected group of "NOH compounds performs excellently as enhancing agents when used together with laccases for bleaching dyes in solution.
Accordingly, the invention provides a method for bleaching a dye in solution comprising contacting, in an aqueous solution, the dye with a laccase and an enhancing agent of the following formula:

and B is H, or C1-C4 unbranched alkyl wherein said alkyl may contain ether groups, and R2, R3, R4, R5 and R6 are H, NH2, COOH, CN, S03H, CH3, C0CH3, N02, 0CH3, NR7R8, C00R9, or NOH-CO-RIO, wherein R7, R8, R9 and RIO are C1-C2 unbranched alkyl.
DETAILED DESCRIPTION OF THE INVENTION
Enhancinq aaencs
- -
The present invention relates to a method for bleaching a dye in solution comprising contacting, in an aqueous solution, the dye with a laccase and an enhancing agent of the following formula:


and B is H, or C1-C4 unbranched alkyl wherein said alkyl may contain ether groups, and R2, R3, R4 , R5 and R6 are H, NH2, COOH, S03H, CN, CH3, C0CH3, N02, 0CH3, NR7R8, C0OR9, or NOH-CO-RIO, wherein R7, R8, R9, and RIO are C1-C2 unbranched alkyl; in particular R2, R3, R4, R5 and R6 are H, COOH, S03H, CH3, C0CH3, 0CH3, NR7R8, or N0H-C0-R9, wherein R7, R8, and R9 are C1-C2 unbranched alkyl; especially at least three of R2, R3, R4, R5 and R6 should be H,
In a preferred embodiment B is H, or C1-C2 unbranched alkyl, and R2, R3, R4, R5 and R6 are H, NH2, COOH, S03H, CN, CH3, C0CH3, N02, 0CH3, NR7R8, C00R9, or NOH-CO-RIO, wherein R7, R8, R9, and RIO are C1-C2 unbranched alkyl; in particular R2, R3, R4, R5 and R6 are H, COOH, S03H, CH3, C0CH3, 0CH3, NR7R8, or N0H-C0-R9, wherein R7, R8, and R9 are C1-C2 unbranched alkyl; especially at least three of R2, R3, R4, R5 and R6 should be H.
In another preferred embodiment B is K, or CH3, and R2, R3, R4, R5 and R6 are H, NH2, COOH, S03H, CN, CH3, C0CH3, N02, 0CH3, NR7R8, C00R9, or NOH-CO-RIO, wherein R7, R8, R9, and RIO are C1-C2 unbranched alkyl; in particular R2, R3, R4, R5 and R6

are H, COOH, S03H, CH3, C0CH3, 0CH3, NR7R8; or N0H-C0-R9, wherein R7, R8, and R9 are C1-C2 unbranched alkyl; especially at least three of R2, R3, R4, R5 and R6 should be H.
In a particular preferred embodiment, the enhancing agent is N-hydroxyacetanilide.
The enhancing agent of the invention may be present in
concentrations of from 1 to 1000 fxM, preferably of from 5 to 500 |J.M, and more preferably of from 10 to 200 \iM.
Preparation of Enhancing Agents
The enhancing agents described in the present application may be prepared using methods well known to those skilled in the art; a general procedure is outlined in Organic Syntheses 61, 1989, p. 187-192. Some of the enhancing agents are also commercially available.
N-hydroxyacetanilide was produced as described in Organic Syntheses 67 1989, p, 187-192.
Enzyme
The laccase enzyme of the invention may typically be
present in concentrations of from 1 to 10000 jig enzyme protein per liter aqueous solution, in particular of from 5 to 2000 fig enzyme protein per liter aqueous solution, especially of from 5
to 1000 fig enzyme protein per liter aqueous solution.
Required molecular oxygen will usually be present in sufficienr quantity from the atmosphere- If more 0. is needed, additional oxygen may be added.
Laccase and Laccase Related Enzvmes
■■
According to the present invention laccase or laccase related enzymes are the preferred enzymes used together with the

selected group of -NOH compounds described above - when a dye in
solution is to be bleached.
In the context of this invention, laccases and laccase
related enzymes comprise any laccase enzyme comprised by the
5 enzyme classification (EC 1.10.3^2), any catechol oxidase enzyme
comprised by the enzyme classification (EC 1.10.3.1), any
bilirubin oxidase enzyme comprised by the enzyme classification
(EC 1.3.3.5) or any monophenol monooxygenase enzyme comprised by the enzyme classification (EC 1.14.18.1). ) The above mentioned enzymes may be derived from plants, bacteria or fungi (including filamentous fungi and yeasts) and suitable examples include a laccase derivable from a strain of Aspergillus, Neurospora, e.g. N. crassa^ Podospora, Botrytis, Collybia, Fames, Lantinus, Pleurotus, Trametes, e.g. T. villosa and T. versicolor, Rhizoctonia, e.g. R. solani, Coprinus, e.g. C- cinereus, C. comatus, C. friesii, and C. plicatilis, Psathyrella, e.g. P. condelleana, Panaeolus, e.g. P. papilionaceus, Myceliophthora, e.g. M. thermophila, Schytalidi-um, e.g. S. thermophilum, Polyporus, e.g. P. pinsitus, Pycnoporus, e.g. P. cinnabarinus, Phlehia, e.g. P. radita (WO 92,01046), or Coriolus, e.g. C. hirsutus (JP 2-238885).
A laccase derived from Coprinus, Myceliophthora, Polyporus, Pycnoporus, Scytalidium or Rhizoctonia is preferred; in particular a laccase derived from Coprinus cinereus, Myceliophthora thermophila, Polyporus pinsitus, Pycnoporus cinnabarinus, Scytalidium thermophilum or Rhizoctonia solani.
The laccase or the laccase related enzyme may furthermore be one which is producible by a method comprising cultivating a host cell transformed with a recombinant DNA vector which carries a DNA sequence encoding said laccase as well as DNA sequences encoding functions permitting the expression of the DNA sequence encoding the laccase, in a culture medium under

conditions permitting the expression of the laccase enzyme, and recovering the laccase from the culture.
Determination of Laccase Activity (LACU)
Laccase activity is determined from the oxidation of syringaldazin under aerobic conditions. The violet colour produced is photometered at 530 nm. The analytical conditions are 19 mM syringaldazin, 23 mM acetate buffer, pH 5.5, 30°C, 1 min. reaction time.
1 laccase unit (LACU) is the amount of enzyme that catalyses the conversion of 1.0 [imole syringaldazin per minute at these conditions.
Determination of Laccase Activity (LAMU)
Laccase activity is determined from the oxidation of syringaldazin under aerobic conditions. The violet colour produced is photometered at 530 nm. The analytical conditions are 19 mM syringaldazin, 23 mM Tris,maleate buffer, pH 7.5, 30*^0, 1 min. reaction time.
1 laccase unit (LAMU) is the amount of enzyme that
catalyses the conversion of 1.0 |amole syringaldazin per minute at these conditions.
Dyes or colorants
In a preferred embodiment, the method of the invention finds application for bleaching of a textile dye or colorant or textile dyes or colorants in solution.
Colorants and dyes are broad classes of natural and synthetic compounds. The following description of dyes,colorants are not intended to be in any way limiting to the scope of the invention as claimed.

Synthetic textile dyes are typically azo compounds (with one or several azo, or diazenediyl, groups), as exemplified by Acid Red 151, Direcr Blue 1, Direct Brown 44, and Orange II, or anthraquinone compounds such as Acid Blue 45.
Other structural motifs may occur together with these such as Reactive Blue 19.
Some dyes furthermore carry groups capable of coupling to fabric surfaces (reactive dyes), and some dyes are complexed to metal ions. These modifications will often not influence the applicability of the present invention.
A different structure is the indigo moiety, e.g., the soluble dye indigo carmine.
Other dyes and colorants may be of natural origin or may be synthesized as identical to or resembling natural structures. Examples of categories of coloured substances extractable from vegetable sources are polyphenolic, anthocyanine and caretenoid compounds.
Industrial Applications
A specific embodiment of the present invention is provided by household and institutional laundering processes.
In such washing and rinsing processes, dyes and colorants present on fabrics may leach into the washing or rinsing liquor and discoloration of the laundry may result. Bleaching of the coloured compounds in solution by the method of the invention may counteract this undesirable effect.
The present invention may also be used for bleaching stains present on fabric: These stains typically originate from red wine, fruir such as black currant, cherry, strawberry and tomato (in particular ketchup and spaghetti sauce), vegetables such as carrots and beetroot, tea, coffee, spices such as curry and paprika, grass, or ball pens,ink.

In another specific embodiment, dyes leached into process water during textile processing may be bleached by the method of the invention to prevent undesirable deposition.
In another specific embodiment, the method of the invention finds application in treatment of waste water, e.g., waste water from the chemical or pharmaceutical industry, from dye manufacturing, from dye-works, or from the textile industry, the method comprising treatment of the waste water with a laccase in the presence of an enhancing agent of the invention.
In the above mentioned processes and in other applications of the invention, the enhancing agent may be added at the beginning of the process or later, in one or several additions.
Detergent Compogitions
The enhancing agent of the invention may be added to and thus become a component of a detergent composition.
The detergent composition of the invention may for example be formulated as a hand or machine laundry detergent composition including a laundry additive composition suitable for pre-treatment of stained fabrics and a rinse added fabric softener composition, or be formulated as a detergent composition for use in general household^hard surface cleaning operations, or be formulated for hand or machine dishwashing operations.
In a specific aspect, the invention provides a detergent additive comprising the enhancing agent of the invention and a laccase. The detergent additive as well as the detergent composition may comprise one or more other enzymes such as a protease, a lipase, a cutinase, an amylase, a carbohydrase, a cellulase, a pectinase, a mannanase, an arabinase, a galactanase, a xylanase, an oxidase, e.g., a laccase, and,or a peroxidase.
In general the properties of the chosen enzyme(s) should be compatible with the selected detergent, (i.e. pH-optimum, com-

patibility with other enzymatic and non-enzymatic ingredients, etc.), and the enzyme(s) should be present in effective amounts. Proteases: Suitable proteases include those of animal, vegetable or microbial origin. Microbial origin is preferred. Chemically modified or protein engineered mutants are included. The protease may be a serine protease or a metalio protease, preferably an alkaline microbial protease or a trypsin-like protease. Examples of alkaline proteases are subtilisins, especially those derived from Bacillus, e.g., subtilisin Novo, subtilisin Carlsberg, subtilisin 309, subtilisin 147 and subtilisin 168 (described in WO 89,06279) . Examples of trypsin-like proteases are trypsin (e.g. of porcine or bovine origin) and the Fnsa.r±uin protease described in WO 89,06270 and WO 94,25583.
Examples of useful proteases are the variants described in WO 92,19729, WO 98,20115, WO 98,20116, and WO 98,34946, especially the variants with substitutions in one or more of the following positions: 27, 36, 57, 76, 87, 97, 101, 104, 120, 123, 167, 170, 194, 206, 218, 222, 224, 235 and 274.
Preferred commercially available protease enzymes include
Alcalase™, Savinase™, Primase™, Duralase™, Esperase™, and Kannase™ (Novo Nordisk A,S) , Maxatase™, Maxacal""^, Maxapem™, Properase™, Purafect™, Purafect OxP™, FN2™, and FN3™ (Genencor International Inc.i.
Lipases: Suitable lipases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Examples of useful lipases include lipases from Humicola (synonym Thermomyces) , e.g. from H. lanuginosa (T. lanuginosus) as described in EP 258 068 and EP 3 05 216 or from H. insolens as described in WO 96,13580, a Pseudomonas lipase, e.g. from P. alcaligenes or P. pseudoalcaligenes (EP 218 272) , P. cepacia (EP 331 376), P. stutzeri (GB 1,372,034), P.

fluorescens, Pseudomonas sp. strain SD 705 (WO 95,06720 and WO 96,27002), P, wisconsinensis (WO 96,12012), a Bacillus lipase, e.g. from S. subtilis (Dartois et al- (1993), Biochemica et Biophysica Acta, 1131, 253-360), B. stearothermophilus (JP 64,744992) or B. pumilus (WO 91,16422).
Other examples are lipase variants such as those described in WO 92,05249, WO 94,01541, EP 407 225, EP 260 105, WO 95,35381, WO 96,00292, WO 95,30744, WO 94,25578, WO 95,14783, WO 95,22615, WO 97,04079 and WO 97,07202.
Preferred commercially available lipase enzymes include Lipolase*™, Lipolase Ultra™ and LipoPrime™ (Novo Nordisk A,S) . Amylases.;. Suitable amylases (a and,or P) include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Amylases include, for example, a-amylases obtained from Bacillus, e.g. a special strain of B. licheniformis, described in more detail in GB 1,296,839.
Examples of useful amylases are the variants described in WO 94,02597, WO 94,18314, WO 96,23873, and WO 97,43424, especially the variants with substitutions in one or more of the following positions: 15, 23, 105, 106, 124, 128, 133, 154, 156, 181, 188, 190, 197, 202, 208, 209, 243, 264, 304, 305, 391, 408, and 444.
Commercially available amylases are Duramyl™, Termamyl™, Fungamyl™ and BAN™ (Novo Nordisk A,S) , Rapidase™ and Purastar™ (from Genencor International Inc.).
rf»nii1ases: Suitable cellulases include those of bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Suitable cellulases include cellulases from the genera Saciiius, Pseudomonas, Humicola, Fusarium, Thielavia, Acremonium, e.g. the fungal cellulases produced from Hxmicola insolens, Myceliophthora thermophila and Fusarium oxysporum dis-

closed in US 4,435,307, US 5,648,263, US 5,691,178, US 5,776,757 and WO 89,09259.
Especially suitable cellulases are the alkaline or neutral cellulases having colour care benefits. Examples of such cellulases are cellulases described in EP 0 495 257, EP 0 531 372, WO 96,11262, WO 96,29397, WO 98,08940, Other examples are cellulase variants such as those described in WO 94,07998, EP 0 531 315, US 5,457,046, US 5,686,593, US 5,763,254, WO 95,24471, WO 98,12307 and PCT,DK98,00299.
Commercially available cellulases include Celluzyme™, and
Carezyme™ (Novo Nordisk A,S) , Clazinase''^'^, and Puradax HA™
(Genencor International Inc.), and KAC-500(B)™ (Kao Corporation).
Peroxidases,Oxidagfifi: Suitable peroxidases,oxidases include those of plant, bacterial or fungal origin. Chemically modified or protein engineered mutants are included. Examples of useful peroxidases include peroxidases from Coprinus, e.g. from C. cinereus, and variants thereof as those described in WO 93,24618, WO 95,10602, and WO 98,15257.
Commercially available peroxidases include Guardzyme™ (Novo Nordisk A,S).
The detergent enzyme (s) may be included in a detergent composition by adding separate additives containing one or more enzymes , or by adding a combined additive comprising all of these enzymes. A detergent additive of the invention, i.e. a separate additive or a combined additive, can be formulated e.g. as a granulate, a liquid, a slurry, etc. Preferred detergent additive formulations are granulates, in particular non-dusting granulates, liquids, in particular stabilized liquids, or slurries.
Non-dusting granulates may be produced, e.g., as disclosed in US 4,106,991 and 4,661,452 and may optionally be coated by methods known in the art. Examples of waxy coating materials are

poly(ethylene oxide) products (polyethyleneglycol, PEG) with mean molar weights of 1000 to 20000; ethoxylated nonylphenols having from 16 to 50 ethylene oxide units; ethoxylated fatty alcohols in which the alcohol contains from 12 to 20 carbon atoms and in which there are 15 to 80 ethylene oxide units; fatty alcohols; fatty acids; and mono- and di- and triglycerides of fatty acids. Examples of film-forming coating materials suitable for application by fluid bed techniques are given in GB 1483591. Liquid enzyme preparations may, for instance, be stabilized by adding a polyol such as propylene glycol, a sugar or sugar alcohol, lactic acid or boric acid according to established methods. Protected enzymes may be prepared according to the method disclosed in EP 238,216.
The detergent composition of the invention may be in any convenient form, e.g., a bar, a tablet, a powder, a granule, a paste or a liquid. A liquid detergent may be aqueous, typically containing up to 70 % water and 0-3 0 % organic solvent, or nonaqueous .
The detergent composition comprises one or more surfactants, which may be non-ionic including semi-polar and,or anionic and,or cationic and,or zwitterionic. The surfactants are typically present at a level of from 0.1% to 60% by weight.
When included therein the detergent will usually contain from about 1% to about 40% of an anionic surfactant such as linear alkylbenzenesulfonate, alpha-olefinsulfonate, alkyl sulfate (fatty alcohol sulfate), alcohol ethoxysulfate, secondary alkane-sulfonate, alpha-sulfo fatty acid methyl ester, alkyl- or alken-ylsuccinic acid or soap.
When included therein the detergent will usually contain from about 0.2% to about 40% of a non-ionic surfactant such as alcohol ethoxylate, nonylphenol ethoxylate, alkylpolyglycoside, alkyldimethylamineoxide, ethoxylated fatty acid monoethanolamide,

fatty acid monoethanolamide, polyhydroxy alkyl fatty acid amide, or N-acyl N-alkyl derivatives of glucosamine ("glucamides").
The detergent may contain 0-65 % of a detergent builder or complexing agent such as zeolite, diphosphate, triphosphate, phosphonate, carbonate, citrate, nitrilotriacetic acid, ethyle-nediaminetetraacetic acid, diethylenetriaminepentaacetic acid, alkyl- or alkenylsuccinic acid, soluble silicates or layered silicates (e.g. SKS-6 from Hoechst).
The detergent may comprise one or more polymers. Examples are carboxymethylcellulose, poly(vinylpyrrolidone) , poly (ethylene glycol) , poly(vinyl alcohol), poly(vinylpyridine-N-oxide) , poly(vinylimidazole) , polycarboxylates such as polyacry-lates, maleic,acrylic acid copolymers and lauryl methacry-late,acrylic acid copolymers.
The detergent may contain a bleaching system which may comprise a H2O2 source such as perborate or percarbonate which may be combined with a peracid-forming bleach activator such as tetraacetylethylenediamine or nonanoyloxybenzenesulfonate. Alternatively, the bleaching system may comprise peroxyacids of e.g. the amide, imide, or sulfone type.
The enzyme(s) of the detergent composition of the invention may be stabilized using conventional stabilizing agents, e.g., a polyol such as propylene glycol or glycerol, a sugar or sugar alcohol, lactic acid, boric acid, or a boric acid derivative, e.g., an aromatic borate ester, or a phenyl boronic acid derivative such as 4-formylphenyl boronic acid, and the composition may be formulated as described in e.g. WO 92,19709 and WO 92,19708,
The detergent may also contain other conventional detergent ingredients such as e.g. fabric conditioners including clays, foam boosters, suds suppressors, anti-corrosion agents, soil-suspending agents, anti-soil redeposition agents, dyes, bacteri-

cides, optical brighteners, hydrotropes, tarnish inhibitors, .or perfumes,
It is at present contemplated that in the detergent compositions any enzyme may be added in an amount corresponding to 0.01-100 mg of enzyme protein per liter of wash liqour, preferably 0.05-5 mg of enzyme protein per liter of wash liqour, in particular 0.1-1 mg of enzyme protein per liter of wash liqour.
The enhancing agent of the invention and a laccase may additionally be incorporated in the detergent formulations disclosed in WO 97,07202 which is hereby incorporated as reference.
The following examples further illustrate the present invention, and they are not intended to be in any way limiting to the scope of the invention as claimed.
EXAMPLE 1
Bleaching of methyl orange using various laccases and various NOH-type enhancing agents
Materials and methods
Enzymes
Recombinant Coprinus cinereus laccase (rCcL), produced as described in WO 97,08325, dialyzed against borate pH 9, 57.5 LAMU,ml.
Recombinant Myceliophthora thermophila laccase (rMtL), produced as described in WO 95,33836, 1419 LAMU,ml.
Recombinant Polyporus pinsitus laccase, produced as described in WO 96,00290, 1330 LACU,ml.
Buffer
Britton-Robinson buffer is composed of:
0.1 M phosphate

0.1 M borate 0,1 M acetate
Dye
Methyl orange (Merck, Germany)
Enhancing agents
N-Hydroxyacetanilide
l-Hydroxybenzotriazole
2-Hydroxypyridine-N-oxide
N-Benzoyl-N-phenylhydroxylainine
Benzoic acid[6-(methylsulphonyl)indol-1-yl]ester (PFC-202)
Cyanuric acid
3-Hydroxy-l, 2,3-benzotriazin-4(3H)-one
N-hydroxyphthalimide
2-Ethyl-5-phenylisoxazolium-4'-sulfonate, H20
p,p'-Azoxydiphenetole
Quinoline-N-oxide
Iso-quinoline-N-oxide
di-2-pyridylketone oxime
Bleaching assay Final cone.
50 \il Methyl orange, AbsU^^^rim - 7 1.4 AbsU
125 \il 0,1 M Britton-Robinson buffer 50 itiM
25 pi 2 mM mediator (or water) 0,2 mM 50 pi laccase dilution Reactions were started by addition of enzyme. Absorbance at 4 64 nm was followed for 3 minutes (readings every 5 seconds) on a Cobas Fara at 30^C. Initial bleaching rates were determined 3 from the first linear part of the progress curves.

Results and discussion
The N-OH compounds listed above were tested as laccase mediators in bleaching of methyl orange with three recombinant laccases (rPpL, rMtL and rCcL) at various pH values. All the kinetic data are summarized in Tables 1-3. Large negative numbers represent the best performance.
It can be seen from the Tables that bleaching with 0=C-N-OH types enhancing agents (see N-Hydroxyacetanilide) are surprisingly good compared with the other N-OH types enhancing agents.

Table 1. Initial changes per minute in A464nm of methyl orange using rCcL (rCcL solution diluted 1:200).


Table 2. Initial changes per minute in A4 64nin of methyl orange using rMtL (rMtL solution diluted 1:300).


Table 3. Initial changes per minute in A464nm of methyl orange using rPpL (rPpL solution diluted 1:200).
EXAMPLE 2
Bleaching of methyl orange with laccase and new -NQH-CQ- type mediators
) Materials and methods
Enzymes
Polyporus pinsitus laccase as described in Example 1.

Dye
Methyl orange (Merck, Germany)
Enhancinq aaents
N-Hydroxyacetanilide
N-{4"Cyanophenyl)-N-hydroxyacetamide (CAS 80584-65-2)
Bleaghing a.gsay
SO fil 0.1 mg,ml methyl orange 125 fil 0.1 M Britton-Robinson buffer (see example 1) 25 ,xl 2 mM mediator or water (as reference) 50 IJLI laccase dilution (1:400)
Methyl orange, buffer and mediator are mixed in a micro-titre plate and the reaction is started by addition of laccase. Absorbance is measured at 450 nm after 15 min.
Results and discussion
N-Hydroxyacetanilide and N-(4-cyanophenyl)-N-hydroxyacetamide were tested as mediators in bleaching of methyl orange with a laccase at pH 4-6, The kinetic data are summarized in Table 4. Low values represent the best performance.
The data show N-(4-cyanophenyl)-N-hydroxyacetamide to be as effective as N-Hydroxyacetanilide at bleaching a dye in solution.

Table 4. Absorbance measured at 450 nm after 15 minutes.

EXAMPLE 3
Bleaching of various dyes with laccrase and N-Hvdroxvacetanilide
Materials and methods
Enzymes
Polyporus pinsitus laccase as described in Example 1, except
that the concentration is 1726 LACU,ml.
Dyes
Acid blue 113 (Aldrich)
CSB (Aldrich)
Acid blue 45 (Aldrich)
Cibachron Marine (Ciba Specialty Chemicals)
Enhancing agent N*Hydroxyacetanilide
Bleaching assay
50 dye solution 125 0.1 M Britton-Robinson buffer, pH 5 (see example 1) 25 ,il 2 mM mediator or water (as reference) 50 ,il laccase dilution (1:400) or water (as reference)
Dye, buffer and mediator are mixed in a micro-titre plate and the reaction is started by addition of laccase. Absorbance is measured at 595 nm after 5 min.
Results and discussion
N-Hydroxyacetanilide was used as mediator in bleaching of various dyes with a laccase. The kinetic data are summarized in Table 5. Low values represent the best performance.
The data shows that the mediator enhances bleaching of several different dyes.


Table 5. Absorbance measured at 595 nm after 5 minutes.

CLAIMS
1. A method for bleaching a dye in solution comprising contacting, in an aqueous solution, the dye with a laccase and 5 an enhancing agent of the following formula:

and B is H, or C1-C4 unbranched alkyl wherein said alkyl may contain ether groups, and R2, R3, R4, R5 and R6 are H, NH2, COOH, S03H, CN, CH3, C0CH3, N02, 0CH3, NR7R8, C00R9, or NOH-CO-RIO, wherein R7, R8, R9 and RIO are C1-C2 unbranched alkyl.
2. A method according to claim 1, in which the enhancing agent
is N-hydroxyacetanilide.
3. A method according to claim 1, in which the laccase is a
microbial laccase.
4. A method according to claim 3, wherein the laccase is derived
from Coprinus, Myceliophthora, Polyporus, Pycnoporus,
Scytalidium or Rhizoctonia.

5. A mechod according to claim 4, wherein the laccase is derived
from Coprinus cinereus, Myceliophthora thermophila, Polyporus
pinsi tus, Pycnoporus cirmaharinus, Scytalidium thennophilim or
' Rhizoctonia solani.
6. A method according to any of claims 1-5, in which said method
is a method for inhibiting the transfer of a textile dye from a
dyed fabric to another fabric when said fabrics are washed
I together in a wash liquor.
7. A method according to claim 6, in which the enhancing agent
is added at the beginning of, or during the process.
8. A method according to claim 1, in which the concentration of
the enhancing agent is in the range of from 1 to 1000
9. A detergent composition comprising a laccase, a surfactant
and an enhancing agent of the formula:


and B is H, or C1-C4 unbranched alkyl wherein said alkyl may contain ether groups, and R2, R3, R4, R5 and R6 are H, NH2, COOH, S03H, CN, CH3, C0CH3, N02, 0CH3, NR7R8, C00R9, or NOH-CO-RIO, wherein R7, R8, R9 and RIO are C1-C2 unbranched alkyl.
10, A detergent composition according to claim 9, in which the enhancing agent is N-hydroxyacetanilide.
11• A detergent composition according to claim 9, wherein the laccase is derived from Coprinus, Myceliophthora, Polyporus, Pycnoporus, Scytalidium or Rhizoctonia.
12. A detergent composition according to claim 11, wherein the laccase is derived from Coprinus cinereus, Myceliophthora thermophila, Polyporus pinsi tus, Pycnoporus cinnabarinus, Scytalidium thermophilum or Rhizoctonia solani.
13. A detergent composition according to any of claims 9-12, which further comprises one or more other enzymes, in particular a protease, a lipase, an amylase, a cellulase, and/or a cutinase.

14. A method for bleaching a dye in solution, substantially as hereinabove described and exemplified.