LECTIN-CONTAINING SEPARATION AGENT

Abstract: A separation agent composed of a water unsoluble solid substance with a covalently bound lectin. Said solid substance is structurally composed of a water unsoluble silica or silicate material as basic material and, via a linkage to silicon atoms in the silica or silicate material, a covalently bound lectin.

Description: LECTIN-CONTAINING SEPARATION AGENT This invention relates to a separation agent consisting of a water un¬ soluble solid substance containing a covalently bound lectin. Lectins, especially Concanavalin A, have earlier been bound to solid substances such as agarose. The resulting material has been used for the separation of various carbohydrates, carbohydrate-related substan- . ces, organelles and even whole cells (Concanavalin A as a Tool, H. Bittiger and H. P. Schnebli, John Wiley and Sons, New York, 1976). The polymers .which has been used as basic material in these separation agents, for example agarose and polymethacrylic acid, has the drawback of leading to bad flow characteristics due to poor rigidity of the poly¬ mer and bad separation characteristics. According to the present invention there has now been provided a separa¬ tion agent of the above-mentioned type, which has superior flow and separation characteristics and which is well suited for use in connec¬ tion with for example high performance liquid chro atography (HPLC). The separation agent according to the invention is characterized in that the solid substance structurally is composed of a water unsoluble silica material as basic structure and via a linkage to silicon atoms in said silica or silicate material, a covalently bound lectin. The expression "silica material" is herein intended to mean silicic acid in more or less dehydrated form, including silica. The basic mate¬ rial may be non-porous or porous silica or glass particles, which are known per se as carrier material in several applications, for example . in biochemical determination methods, but can also consist of the inner wall of a tube or be a disk. The lectin is covalently bound to an alky- lene chain which contains 1 -.22, preferably 2 - 18, carbon atoms and optionally being interrupted of one or more oxygen, sulphur or nitrogen atoms and/or being substituated with one or more hydroxyl groups. Ex- cept for the case of amide and ester groups, perferably at most 1 atom of other kind than carbon and hydrogen is bound to one and the same carbon atom in the chain. The alkylene chain is in turn bound, optii - UREAl OMPl ally via an intermediate silicon atom, preferably to an oxygen atom belonging to a hydroxyl group, said hydroxyl group being bound to a silicon atom in the as basic material for the present separation agent used water unsoluble silica or silicate material, or optionally direct- ly to a silicon atom in said basic material. The introduction of the bridge-forming alkylene chain structure and the lectin in the silica or silicate material is preferably performed in two steps. A substituent which corresponds to the alkylene chain and which contains a reactive structure such as for example an epoxy or carboxyl group is introduced in the first step. In the second step the lectin is added which can react with the funcional structure on the silica. In some cases a condensation-promoting agent such as a car- bodimided may also be added. The invention vill be illustrated by means of examples in the follwing text. EXAMPLE 1 PREPARATION OF SILICA COMPRISING EPOXY GROUPS To 20 g porous silica (LiChrosorb Si 1000, 10 -μm, E Merck, Darmstadt, Fedral Republic of Germany), dried at 200 °C over night and then sus- pended in 500 ml Na-dried toluene was added 200 μl triethylamine (po¬ tassium hydroxide-dried) and 10 ml γ-glycidoxy-propyltrimethoxysilane. The mixture was reflux boiled under nitrogen for 16 h in a flask fitted with teflon stirrer. Thereafter the substituted silica was filtered off and washed on a glass filter funnel with toluene, acetone and diethyl ether and finally drysucked. A sample of the obtained product was ana¬ lyzed with respect to epoxy groups (reaction with 3 M sodium thiosϋl- phate for 1 h at pH 7 and determination of librated hydroxyl ions by addition of acid (pH-stat; 0.10 M hydrochloric acid)). Materials based on LiChrosorb Si 1000 contained about 50 μmole epoxy groups/g. OMPI EXAMPLE 2 PREPARATION OF SILICA CONTAINING DIOL GROUPS 3 g silica containing epoxy groups (see example 1) was suspended in 300 ml of 0.03 M hydrochloric acid. The mixture was kept at 50 °C with stirring for 2 hours. The obtained diol-containing material was filter¬ ed and washed with water, ethanol and ether and finally dried at re¬ duced pressure. EXAMPLE 3 PREPARATION OF SILICA CONTAINING ALDEHYDE GROUPS 3 g silica containing diol groups (see example 2) were suspended in 50 ml 90 % acetic acid and 5 g sodium " periodate added in portions. The mixture was stirred carefully for 2 hours at roo -temperature. The al¬ dehyde-containing silica was filtered, washed with water, aceton and ether and dried at reduced pressure. EXAMPLE 4 PREPARATION OF SILICA CONTAINING TRESYL GROUPS 3 g silica containing diol groups (see example 2) was dried in a vacuum ' at 50 °C for 4 hours and then suspended in 20 ml of sodium-dried ace¬ tone. 1 ml of pyridine was added followed by 0.5 ml tresyl chloride under vigorous stirring. The tresyl chloride was obtained from Fluka, Buchs, Switzerland. After 30 min the tresyl group-containing silica was filtered off and washed on a glass filter with 200 ml of acetone, and finally dried under reduced pressure. 'BUREAU OMPI. - .- EXAMPLE 5 PREPARATION OF SILICA CONTAINING BOUND LECTIN (VIA SILICA CONTAINING EPOXY GROUPS) 1 g silica containing epoxy groups (see example 1) was suspended in 5 5 ml 0.1 sodium phosphate buffer pH 8.0, containing 50 mg Concanavalin A (obtained from Sigma, St. Louis, MO, USA). The suspension was stirred carefully for 24 hours at 4 °C. The lectin-containing silica was filter¬ ed off on a glass filter and washed with the above buffer. The Concana¬ valin A-silica was stored moist at 4 C. 10 Lectin-containing silica was suspended in 3 ml of saturated sucrose solution and the spectrum (240 nm - 320 nm) recorded. The absorbance culate the concentration (A . 1 7 1 % at 280 nm was used to cal 28 S % 0n *** 10). A typi¬ cal value is 2 mg Concanavalin A/g silica. EXAMPLE 6 15 PREPARATION OF SILICA SITH BOUND LECTIN (VIA SILICA WITH ALDEHYDE GROUPS) 1 g silica with aldehyde groups (see example 3) was suspended in 5 ml 0.1 M sodiu phosphate buffer pH 7.5 containing 100 mg Concanavalin A. • » Q The suspension was stirred carefully for 16 hours at 4 C. 100 mg of 20 sodiu -borohydride was then added in portions under 30 min. After 4 hours the lectin-containing silica was isolated, washed, analyzed and stored as described in example 5. Typical lectin content is 60 mg Con¬ canavalin A/g silica. EXAMPLE 7 25 PREPARATION OF SILICA CONTAINING LECTIN (VIA SILICA CONTAINING TRESYL GROUPS) 1 g silica containing tresyl groups (see example 4) was suspended in OfPI 5 ml 0.1 M sodium phosphate pH 7.5 containing 100 mg Concanavalin A. The suspension was stirred carefully for 16 hours at 4 C. Any remain¬ ing tresyl groups were subsequently eliminated by treatment with Tris- HC1 buffer (0.1 M, pH 7.5) for 1 hour. The lectin-containing silica was isolated, washed, analyzed and stored as described in example 5. Typi¬ cal lectin content is 60 mg Concanavalin A/g silica. EXAMPLE 8 SEPARATIONS OF SUGAR WITH LECTIN-CONTAINING SILICA The separation was carried out with HPLAC-equipment (High Performance Liquid Affinity Chromatography). An Altex pump (model 110 from Altex Scientific Inc., Berkley, Califonia, USA) was used together with a UV • detector (SpectroMonitor III from Laboratory Data Control, Riviera Beach, Florida, USA). Lectin-containing silica according to examples 5, 6 and 7 was packed in stainless steel columns (5 x 0.5 cm or 5 x 10 cm; total volume 1 and 2 ml respectively) using a packing technique described by P. A. Bristow __ aj_. , 0. Chromatography,.131 (1977) 57. The lectin-containing ' silica was kept suspended n 50 % sucrose*during the packing procedure. The chromatographic runs were carried out at room temperature. The pressure drop was 1 - 2 MPa at a flow rate of 1 ml/min. A mixture of glycosides (1 - 10 μg) was injected in the flow, the reten¬ tion times noted and the respective k'-values, "column capacity ratio" calculated: k' = ———-. T P is the retention time of. the glycoside To in question, T 0 is the "retention" time for an unretarded ' substance. A high k'-value indicates a strong interaction between the lectin-con¬ taining silica and the glycoside. The table shows representative results from a large number of separa¬ tion experimeβts. In all experimnts a mixture of p-nitrophenyl-α-D- glucoside, p-nitrophenyl-β-D-glucoside and p-nitrophenyl-α-D-mannoside was resolved. The table give k'-values for p-nitrophenyl-α-D-mannoside in combination with different types of Concanavalin A-silica. The table shows that the k'-value for the mannoside could be varied between 0.5 and 17. The k'-value for the -D-glucoside could be varied up to 3 and the k'-value for the β -D-glucoside could be varied up to 0.7 (not shown in the table). Preparation number: Pore size (A) 100 100 1000 1000 1000 1000 Coupl ing • according to exampl e number: Concanavalin A content (mg/g) 10 25 60 80 60 k* 0.5 2.1 3.8 16 12 17 EXAMPLE 9 SEPARATION AND PURIFICATION OF THE GLYC0PR0TEIN PEROXIDASE BY CHROMATOGRAPHY ON LECTIN-CONTAINING SILICA Equipment and procedures as in example 8 A sample containing 4 mg of protein in 4 ml 0.1 M phosphate buffer pH 7 was injected on a solumn containing Concanavalin A-silica (60 mg/g; prepared as in example 6). The peroxidase was absorbed on the column whereas remaining protein passed the column unretarded. A pulse of • α-D-methyl-glucoside (4 ml; 25 mM) eluted a pure peroxidase as judged from spectrophoto etric data. A gradient, 0 - 20 M, of the same methyl- glucoside could also be used to elute the peroxidase. The purification lasted in the first case 15 minutes and in the second case 30 minutes. O.MPI EXAMPLE 10 PEROXIDASE-BINDING CAPACITY OF CONCANAVALIN A-SILICA Equipment and procedures essientially as in example 8. Through a column filled with 1 g of Concanavalin A-silica (60 mg/g; prepared as in example 6) was pumped a peroxidase containing solution until the column became saturated. The binding capacity was then cal¬ culated as 12 mg peroxidase/g of silica. EXAMPLE 11 SEPARATION AND PURIFICATION OF THE GLYCOPROTEIN GLUCOSE OXIDASE BY CHROMATOGRAPHY ON LECTIN-CONTAINING SILICA Equipment and ' procedures as in example 8 A sample containing 4 mg of protein in 4 ml 0.1 M sodium phosphate buff¬ er, pH 7.0, was injected on a column filled with Concanavalin A-silica (60 mg/g; prepared as in example 6). The glucose oxidase was strongly absorbed to the lectin-containing silica and could not be eluted with methyl glucosi ' de. A pulre of 0.2 M glycine-HCl buffer, pH 2.8, was re¬ quired for elution. the drastic condition for elution did not harm the packing material or the enzyme. EXAMPLE 12 STABILITY OF LECTIN-CONTAINING SILICA One column was used 60 times without any noticeable change of the k'- value for chromatographed substances.

Claims: AMENDED CLAIMS [received by the International Bureau on 02 September 1983 (02.09.83); original claim replaced by amended claims 1 to 3 ] 1) Separation agent for separation of mixtures of molecules, organelles and/or cells containing the molecular species onosaccharides, oli- . gosaccharides, glycoproteins and/or glycolipids, characterized in that the separation agent is composed of a water unsoluble silica or silicate material as basic structure and, via a linkage to silicon atoms in said silica or silicate material, a covalently bound lectin. 2) Separation agent according to claim 1, where said silica or silicate material is comprised of porous silica. 3) Separation agent according to claim 1 , where said lectin is Con¬ canavalin A.

Inventors: BORCHERT AXEL, LARSSON PER-OLOF, MOSBACH KLAUS, BORCHERT, AXEL, LARSSON, PER-OLOF, MOSBACH, KLAUS
Applicants: BORCHERT AXEL, LARSSON PER OLOF, MOSBACH KLAUS, BORCHERT, AXEL, LARSSON, PER-OLOF, MOSBACH, KLAUS
Application year: 1983
Main classification: B01D15
IPC codes: B01D15, B01J20, C07H15, C07K14, C12N9, G01N30