1555 results about "Glycine" patented technology

A pharmaceutical composition comprising a protein arginine methyltransferase 5 (PRMT5) inhibitor and a KRASG12C (Kirsten rat sarcoma viral oncogene homolog glycine-to-cysteine) inhibitor. The pharmaceutical composition can be used for treating various cancers, comprising solid tumors. The combined product can be used for treating any number of diseases associated with PRMT5 and / or KRASG12C.

The invention discloses a high-performance carbonyl reductase mutant and application thereof in synthesis of a series of chiral alcohols. The high-performance carbonyl reductase mutant is obtained by performing the following mutations on an amino acid sequence as shown in SEQ ID NO.2: the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine, and the 69th alanine mutates into any one of lysine, leucine, aspartic acid or asparagine; and / or the 100th glycine is mutated into any one of glutamic acid, serine, lysine or asparagine. Compared with a wild type enzyme, the thermal stability and the catalytic activity of the obtained mutant are remarkably improved, particularly, single point mutants Mut-A69N, Mut-G100E and Mut-G100N and a combined mutant Mut-A69N-G100N show excellent relative enzyme activity, thermal stability and substrate tolerance. The mutant has high catalytic activity and stability to various chiral alcohols, and the contradiction that the traditional carbonyl reductase is easy to inactivate at high temperature and the catalytic efficiency is difficult to achieve at the same time is solved. The invention provides an efficient and stable enzyme catalysis tool for green biological preparation of chiral drug intermediates.

The invention relates to hydrogel loaded with oxygen self-producing nanoparticles as well as a preparation method and application of the hydrogel. The preparation method comprises the following steps: 1, taking cross-linked methacrylamide silk fibroin and hyaluronic acid modified by arginine-glycine-aspartic acid peptide as base materials, and loading self-oxygen-producing nano particles CaO2 (at) PVP (at) Cu-EGCG, and the self-oxygen-producing nano particles CaO2 (at) PVP (at) Cu-EGCG are prepared by coating Cu-EGCG on calcium peroxide nano particles modified by PVP modified polyvinylpyrrolidone. The hydrogel can improve energy metabolism and regulate immune environment through dual mechanisms, realizes efficient promotion of myocardial repair, and provides a new strategy and thought for tissue regeneration and functional recovery after myocardial infarction.

The invention discloses a cyclic nonapeptide with repairing and anti-oxidation effects and application of the cyclic nonapeptide, the amino acid sequence of the cyclic nonapeptide is cyclic (arginine-glycine-aspartic acid-serine-arginine-lysine-valine-lysine-serine), the prepared cyclic nonapeptide has the repairing and anti-oxidation effects, and the cyclic nonapeptide has the repairing and anti-oxidation effects. The composition can be applied to preparation of cosmetics with repairing and / or anti-oxidation effects.

The invention provides a plant lactobacillus TH13, and the preservation number of the plant lactobacillus TH13 is CGMCC (China General Microbiological Culture Collection Center) NO.32112. The plant lactobacillus TH13 provided by the invention can be used for fermenting folium cortex eucommiae and enzymatically hydrolyzed bone meal, and the fermentation product of the plant lactobacillus TH13 has high content of chlorogenic acid, proline, glycine and lysine. The fermentation product can significantly improve the content of alkaline phosphatase (ALP) and osteocalcin (OCN) in mouse serum and reduce the content of tartrate-resistant acid phosphatase (TRACP). Therefore, the fermentation product can significantly improve the bone mineral density of the femur, increase the number of bone trabecula and significantly reduce the separation degree of the bone trabecula, thereby promoting bone formation of a mouse with senile osteoporosis, inhibiting bone resorption and improving senile bone loss and bone microstructure deterioration. The preparation method of the probiotic preparation containing the plant lactobacillus and the probiotic fermentation product is simple, and large-scale production can be realized.

The invention provides an amino acid frosted cleaning composition as well as a preparation method and application thereof. The amino acid frosted cleaning composition comprises a surfactant, an amino acid composition, a thickening agent, a humectant, an antioxidant, a pH regulator and water, the surfactant is a combination of cocoyl glycinate, cocamidopropyl hydroxy sulfobetaine, sodium cocoyl methyl taurine taurate, sulfonic acid hydroxypropyl ester lauryl glucoside cross-linked polymer sodium and glycolipid. According to the invention, a mild surfactant system with amino acid as a main component is adopted, so that the shampoo has rich and fine foam, quick foaming performance and easy washing performance, and the skin feeling is smooth and soft after washing. In addition, the system contains suspended crystal frosted particles formed by self-assembly of the amino acid composition, the appearance is novel, the better efficacy performance is achieved, and meanwhile the cleaning effect and the use comfort are improved.

The invention relates to a method for improving chemiluminescence immunoassay sensitivity of magnetic particles, a detection kit and application thereof, firstly, magnetic beads are coupled with an antibody, then magnetic beads are sealed to obtain a magnetic bead coated antibody, sealing comprises pre-sealing and second-step sealing, glycine and ethanolamine are added in the pre-sealing process, and in the second-step sealing process, glycine and ethanolamine are added in the second-step sealing process. Casein hydrolysate and dodecyl dimethyl amine ethyl lactone are added; then coupling the antibody with alkaline phosphatase or streptavidin to obtain an alkaline phosphatase labeled antibody or a streptavidin labeled antibody; the magnetic bead coated antibody, the alkaline phosphatase labeled antibody or the streptavidin labeled antibody is used for sample detection. The method is high in sensitivity and wide in detection range, is adaptive to a common immunoassay instrument, does not need expensive equipment, and is also simple to operate; in addition, the AMH concentration with extremely low concentration can be accurately detected.

The invention discloses an anti-aging face cream suitable for sensitive skin and a preparation method of the anti-aging face cream. The anti-aging face cream comprises 1-10 wt% of a supramolecular eutectic compound, 10-30 wt% of an auxiliary material and the balance of deionized water, the supramolecular eutectic compound comprises an anti-aging component, a supramolecular eutectic agent and Neosol-Aqulio, wherein the supramolecular eutectic agent is used for forming a supramolecular eutectic with the anti-aging component, and the Neosol-Aqulio is dispersed in the supramolecular eutectic; wherein the anti-aging component comprises oleuropein and hydroxytyrosol, and the supramolecular eutectic agent is nicotinamide, or a mixture of capryloyl glycine and betaine. Neosol-Aqulio, a supramolecular eutectic agent and an anti-aging component are utilized to form a supramolecular eutectic, so that active component delivery is facilitated, efficient transdermal absorption is realized, permeability, stability and mildness of the anti-aging active component are improved, the problem of sensitive skin cuticle permeation is solved, irritation of a traditional penetration enhancer is avoided, and the penetration enhancer is suitable for clinical application. The double effects of efficient permeation and mild anti-aging are realized.

The invention relates to a crystal type mild cleansing cream and a preparation method thereof, and belongs to the technical field of cosmetics. The crystalline mild cleansing cream is prepared from the following components: glycerol, a mixed amino acid surfactant, lauryl hydroxyl sulfobetaine, disodium lauryl sulfosuccinate, a chelating agent, citric acid, a preservative, a skin conditioning component and water, wherein the mixed amino acid surfactant is formed by mixing solid potassium cocoyl glycinate, solid sodium cocoyl glycinate and a sodium cocoyl glycinate aqueous solution; the cleansing cream comprises the following components in percentage by mass: 25%-35% of glycerol, 18%-25% of active ingredients of the mixed amino acid surfactant, 3%-4.5% of lauryl hydroxyl sulfobetaine and 1%-3% of disodium lauryl sulfosuccinate. According to the crystal type mild cleansing cream, no extra thickening agent component is used, the cream body which is good in texture and stable is obtained only through synergistic thickening of the three amino acid surfactants, irritation is small, sensitive skin friendliness is achieved, the preparation technology is simple, and cost is low.

The invention relates to a radionuclide-labeled glucose derivative molecular probe and application thereof, and belongs to the technical field of nuclear medicine. According to the present invention, propargyl glycine is used to synthesize an amino acid skeleton, and the amino acid skeleton reacts with glucose azide to prepare a series of radionuclide-labeled glucose derivative molecular probes, such as [68Ga] Ga-NOTA-SDG, [68Ga] Ga-NOTA-DDG, [68Ga] Ga-NOTA-TDG, [68Ga] Ga-DOTA-SDG, [68Ga] Ga-DOTA-DDG and the like; the glucose derivative molecular probe labeled by the series of radionuclides has the advantages of being simple and rapid in labeling, high in radiolabeling yield and good in stability, can accurately position tumors, has good tumor uptake and lower non-target tissue uptake, and has great application prospects in preparation of broad-spectrum tumor imaging agents.

The invention discloses a 3 '-phosphoadenosine-5'-phosphoryl sulfate synthetase mutant and an application of the 3 '-phosphoadenosine-5'-phosphoryl sulfate synthetase mutant. Compared with a wild enzyme amino acid sequence as shown in SEQ ID NO.1, the amino acid sequence of the 3 '-adenosine-5'-phosphoryl sulfate synthetase mutant has one or two mutations in the 101 site, the 207 site and the 560 site; preferably, phenylalanine at the 101 site is mutated into tryptophan; cysteine at the 207th site is mutated into glycine; phenylalanine at the 560th site is mutated into tryptophan. The invention also provides a synthesis method and application of the 3 '-adenosine-5'-phosphoryl sulfuric acid. The APS intermediate product inhibition effect of hPAPSS1 is relieved through a point mutation technology, the substrate affinity of hPAPSS1 to ATP is improved, and a mutant enzyme with a high PAPS conversion rate is obtained; and the bifunctional enzyme hPAPSS1 is synthesized by heterologous expression of PAPS in escherichia coli, so that the acquisition of the enzyme is simplified, and the synthesis efficiency of PAPS is improved.

The present invention belongs to the field of biotechnology, and specifically relates to a GmSGT2 gene related to plant height and branch development, and a mutant thereof and the use thereof. A Glycine max mutant having fewer branches and decreased plant height is obtained by means of EMS mutagenesis, and a target gene thereof that is located by means of a map-based cloning technique is a GmSGT2 gene of Hedou 12. It is found through searching that the gene encodes soyasapogenol B glucuronide galactosyltransferase, and can galactosylate soyasapogenol B monoglucuronide, thereby affecting the plant height of Glycine max and reducing the branches of Glycine max. Therefore, the GmSGT2 mutant can be used for cultivating dwarf high-yield Glycine max varieties, and is of great significance in the breeding of ideal plant types of Glycine max and research on important agronomic traits of plants. The mutant has broad application prospects and great research value with regard to understanding the plant height and branch regulation mechanism of Glycine max and improving the process of Glycine max breeding; and can provide an excellent germplasm resource stock for regulating the close planting and high-yield breeding of Glycine max.

The invention provides transparent shampoo with fluffy and anti-dandruff effects and a preparation method of the transparent shampoo. The shampoo comprises the following components in percentage by weight: 10%-20% of sodium laureth sulfate; 0.5% to 10% of ammonium laureth sulfate; 0.5%-10% of cocamidopropyl betaine, 0.5%-10% of 0.5%-10% of coconut oil fatty acid monoethanolamide; 0.5% to 10% of decyl glucoside; 0.6% to 1.5% of capryloyl glycine; 0.1% to 1% of cationic guar gum; 0.1% to 1% of polyquaternium-10; 0.1% to 1% of polyquaternium-11; 0.1% to 1% of polyquaternium-51; 0.01% to 2% of magnolol; 0.01% to 2% of menthol; 0.1%-1% of sodium chloride; 0.1%-1% of citric acid; and 0.1%-1% of disodium EDTA. The shampoo disclosed by the invention has the effect of improving the combing performance in a dry hair state, can effectively improve the smoothness of hair and the touch comfort during use, and also has a supporting effect and antibacterial and anti-dandruff effects. According to the shampoo process, the clarity and appearance stability of the product are remarkably improved, and the shampoo can be kept in a transparent and uniform state for a long time.

The present invention belongs to the technical field of biological prevention and treatment for viral diseases. Disclosed in the present invention are a tomato disease-resistant gene mutant, and the use thereof in the prevention and treatment of ToBRFV. It is found in the present invention that mutating the nucleotide at position 1927 of the coding region sequence of tomato Tm-22 gene from G to A, or mutating the amino acid at position 643 of the LRR domain of a protein that is encoded by tomato Tm-22 gene from glycine to arginine can remarkably reduce the accumulation level of ToBRFV capsid protein (CP). The gene (named Tm-22-Mut5) can serve as a novel ToBRFV resistant gene, and also retains the resistance to TMV, ToMV and ToMMV. The Tm-22-Mut5 and a pre-screened Tm-22-Mut3-1 mutant (tyrosine at position 767 of the LRR domain thereof is mutated to phenylalanine) undergo combinatorial mutagenesis to obtain a mutant Tm-22-Mut6. Analysis shows that the Tm-22-Mut6 can remarkably reduce the accumulation level of the ToBRFV capsid protein. Compared with the pFGCTm-22-Mut3-1 mutant obtained by screening in the previous research and the newly obtained mutant Tm-22-Mut5, the Tm-22-Mut6 has further improved resistance to ToBRFV.

The invention discloses a diluent for whole blood lateral immunochromatography detection as well as a preparation method and a detection method thereof, and belongs to the technical field of immunochromatography detection. The diluent solves the technical problems of unsmooth chromatography, background interference, poor stability of detection results and the like caused by red blood cells during direct detection of whole blood samples. The diluent comprises a buffer system, an osmotic pressure regulator glycine, a nonionic surfactant polysorbate, an erythrocyte aggregation inducer polyvinylpyrrolidone, a dynamic viscosity regulator trehalose, a blocking protein, a stabilizer combination L-methionine and L-histidine, and a composite formula of water. Red blood cells are effectively induced to gather and intercept on the sample pad through the synergistic effect of all the components, and meanwhile the stability of the chromatography process and the activity of the detection reagent are maintained. The diluent is mainly used for lateral immunochromatography quantitative detection of markers such as pro-enkephalin, C-reactive protein, cardiac troponin I or N-terminal pro-brain natriuretic peptide in a whole blood sample.

The invention relates to the technical field of wastewater treatment, and provides a treatment method of glycine production wastewater. The treatment method of glycine production wastewater comprises the following steps: (1) rectifying glycine wastewater to recover methanol, adding dilute sulphuric acid to adjust the pH value to 2.5-3.0, stirring, and standing; (2) transferring the supernate into another container, adding a ZIF-8 modified material, stirring, standing, filtering, collecting filter residues and filtrate, washing the filter residues with diethyl ether, and recovering urotropine; and (3) evaporating and concentrating the filtrate under the vacuum condition of-0.08 MPa and the temperature of 50-60 DEG C, and separating out high-purity ammonium chloride crystals. According to the treatment method for the glycine production wastewater, the problem that an existing treatment method is poor in removal effect on urotropin in the glycine production wastewater is solved; and the treated glycine production wastewater reaches the discharge standard.

The invention discloses modified hydroxytyrosol as well as a preparation method and application thereof. The provided preparation method of the modified hydroxytyrosol comprises the following steps: in the presence of an acidic solvent, mixing hydroxytyrosol, protease and collagen for reaction, mixing a reaction product with an extraction agent, performing centrifugal layering, and collecting upper-layer components, thereby obtaining the modified hydroxytyrosol, the protease comprises one or two of neutral protease and trypsin. Under the enzymolysis action of protease, the collagen can be decomposed into amino acid monomers such as glycine, proline and hydroxyproline, and the amino acid monomers can be subjected to graft modification with hydroxytyrosol; meanwhile, collagen fragments which are not subjected to enzymolysis also exist, and are subjected to graft modification with hydroxytyrosol in the form of collagen characteristic fragments. The oxidation resistance and the stability of the obtained modified hydroxytyrosol are obviously improved compared with those of unmodified hydroxytyrosol.

The invention discloses a rice large-scale metabolism regulator DGP1 and crop metabolism quality design. The invention finds that the structural domain of the rice DGP1 family protein TIGR01589 targets a plurality of metabolic enzymes and promotes the metabolic enzymes to be transferred to a cell nucleus; the structural domain also has an intervention effect on a light breathing pathway by changing the composition of a glycine decarboxylase compound in mitochondria. Based on a molecular mechanism of DGP1, a chimeric protein ST containing a conservative structural domain and coupled with a chloroplast positioning signal is designed, and genetic engineering modification of pakchoi is realized. The modification strategy not only can guide substrate flow of a central glycolysis pathway to flavonoid biosynthesis, but also can promote accumulation of saccharides derived from photosynthetic products in leaves.

The invention relates to the technical field of separation and purification, in particular to a purification method of eugenol, which comprises the following steps: (a) dissolving crude eugenol in an ethanol aqueous solution to prepare a solution with eugenol mass concentration of 20-30%; (b) adding a composite protective agent into the solution, uniformly stirring and standing to obtain a mixed solution, the composite protective agent comprising modified chitosan, sodium ascorbate and nano-silica; (c) carrying out reduced pressure evaporation on the mixed solution, and recovering the solvent to obtain a concentrated solution; (d) adding the concentrated solution into a glycine aqueous solution with the mass concentration of 1-2%, uniformly stirring and standing; and (e) carrying out segmented temperature control rectification on the concentrated solution treated in the step (d), and collecting a target fraction to obtain the high-purity eugenol. By introducing a novel protective agent system and a staged temperature control rectification technology, the occurrence rate of thermal decomposition and oxidation reaction is remarkably reduced, and the product purity and the production efficiency are improved.

A nutraceutical composition, consisting of Nicotinamide Mononucleotide in a range 250-1000 mg, Spermidine in a range 0.5-10 mg, Rhodiola Rosea in a range 200-600 mg, Cacao in a range 1000-10,000 mg, L-Theanine in a range 50-200 mg, Glucosamine in a range 500-3000 mg, and Hyaluronic acid in a range 50-240 mg, or consisting of Epigallocatechin-3-gallate in a range 100-500 mg, Quercetin in a range 250-1000 mg, Resveratrol in a range 150-1000 mg, Sulforaphane in a range 1-50 mg, and Calcium Alphaketoglutarate in a range 300-2000 mg, or consisting of Microdose Lithium in a range 1-5 mg, Trimethylglycine in a range 500-2000 mg, Glutathione in a range 250-1000 mg, Fisetin in a range 100-1000 mg, Urolithin A in a range 250-2000 mg, Sodium Butyrate in a range 100-3000 mg, Berberine in a range 500-1500 mg, Apigenin in a range 50-500 mg, Cinnamon in a range 1000-6000 mg, and Malate in a range 1000-6000 mg.

The invention provides collagen tripeptide liquid with moisturizing and anti-photoaging effects and a preparation method thereof, and relates to the technical field of bioactive peptides.The preparation method comprises the steps that pretreatment and first-time enzymolysis are conducted, specifically, pretreated fish skin and water are mixed, the pH value is adjusted, compound protease is added for enzymolysis, and first enzymatic hydrolysate is obtained; second-time enzymolysis: adjusting the pH value of the first enzymatic hydrolysate to 6.0-7.5, adding neutral protease for enzymolysis, and then adding aminopeptidase for enzymolysis for 20-40 minutes to obtain second enzymatic hydrolysate; and performing enzyme deactivation, decoloration, separation and purification to obtain collagen tripeptide liquid. Wherein the content of collagen tripeptide, the content of glycine-proline-hydroxyproline and the content of hydroxyproline are high, and good moisturizing and anti-photoaging effects are achieved.

A toothpaste comprising: i) zinc sulfate heptahydrate; ii) glycine; iii) a silica abrasive; iv) greater than 20% by weight of water; wherein the weight ratio of zinc sulfate heptahydrate to glycine is 1: 3 to 2: 1.

The invention belongs to the technical field of nano-enzymes, and particularly relates to a preparation method and application of a porous RuO2 nano-enzyme for detecting creatinine. Comprising the following steps: ultrasonically dispersing Ca (NO3) 2.4 H2O, RuCl3 and glycine in deionized water to obtain a mixed solution A; dissolving sodium alginate in deionized water, and uniformly stirring to obtain a mixed solution B; injecting the mixed solution B into the mixed solution A, slowly stirring to form bimetallic hydrogel, washing with deionized water, and freeze-drying to obtain a solid A; calcining the solid A to obtain a solid B; and adding the solid B into hydrochloric acid for ultrasonic dispersion, stirring for a period of time, and centrifugally washing and drying the precipitate in vacuum to obtain the loose and porous RuO2 nano-particles. The nanoparticles prepared by the invention have abundant pore structures and great specific surface area, active sites can be fully exposed, and the POD enzyme activity is remarkably improved.

The invention discloses a yak bone collagen peptide for improving osteoporosis and preparation and application thereof, and relates to the field of biological medicine, the yak bone collagen peptide comprises collagen peptide with the molecular weight of 500-2000 Daltons, contains a glycine-proline-hydroxyproline tripeptide core structure, can promote osteoblast differentiation and inhibit osteoclast activity, and can be used for treating osteoporosis. The amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine, and the amino acid sequence of the collagen peptide is any one of the following sequences: glycine-proline-hydroxyproline-glycine-glutamic acid-arginine; and the amino acid is glycine, proline, hydroxyproline, serine, leucine and alanine. The yak bone collagen peptide has a unique glycine-proline-hydroxyproline tripeptide structure, the molecular weight is controlled within the range of 500-2000 Daltons, the structure can promote osteoblast differentiation and inhibit osteoclast activity at the same time, and the problem that a traditional osteoporosis treatment medicine is single in function is solved.

The present invention relates to antisense oligonucleotides (AONs) that can mediate RNA editing by binding to a target RNA nucleic acid molecule, preferably an RNA transcript molecule, in a cell and recruiting an endogenous deaminating enzyme in the cell to deaminate a target adenosine in the target RNA molecule to an inosine. The target RNA molecule is a transcript molecule form the SLC10A1 gene that encodes the Na+ / Taurocholate Co-transporting Polypeptide (NTCP), and the target adenosine is the adenosine in the GAC codon coding for aspartic acid (D) at position 24 of the NTCP protein. The deamination of the adenosine changes the amino acid to a glycine (G). The RNA editing of the adenosine will result in a loss-of-function of the NTCP protein, which will result in lowered uptake of bile acids from the portal circulation into the liver, thereby lowering the risk of suffering from disorders related to bile accumulation in the liver.

The invention provides an amino acid compound fertilizer for improving nitrogen and phosphorus utilization rate and a preparation method. The compound fertilizer is based on urea, ammonium sulfate, monoammonium phosphate and potassium chloride according to a specific proportion, glutamic acid / glycine compound amino acid and iron, zinc and boron trace elements are added, and the 18-12-18 proportioning fertilizer with a slow release function is formed through the synergistic effect of amino acid chelation pretreatment and a high tower granulation process. Amino acid competitive inhibition phosphorus immobilization and activation of crop nitrogen metabolic pathways are utilized, a porous coating structure is constructed by means of a modified starch binder, the technical effects that the nitrogen utilization rate is increased by 4% or above and the phosphorus utilization rate is increased by 6% or above are achieved, and the bottleneck of nutrient waste of traditional balanced fertilizers is broken through.

The invention relates to the technical field of concealed project acceptance, and discloses an alpine region bluegrass cold-resistant growth-promoting nutrient solution and an application method thereof.The nutrient solution is composed of main nutrient elements such as nitrogen, phosphorus and potassium and microelements such as iron, manganese, zinc, copper and boron, and amino acid substances such as glycine, alanine and proline are added; therefore, comprehensive and balanced nutrition support is provided. Through a scientific fertilization strategy, including three stages of seed treatment, seedling stage management and growth stage management, and in combination with a drip irrigation system and a foliage spraying technology, efficient utilization of nutrients and healthy growth of plants are ensured. According to the method, the growth speed and biomass of the bluegrass are remarkably increased, the soil structure is improved, the stress resistance of crops is enhanced, the nutrient utilization efficiency is improved, and finally the product quality and market value are improved; the comprehensive benefits are beneficial to promoting the sustainable development of agriculture in alpine regions.

The present application relates to a kind of dipeptide derivative compositions and its preparation method and purposes, the composition includes (a) formula I compound, (b) glycine and (c) antioxidant, the composition has good adjuvant compatibility, the impurity content of lyophilized preparation prepared according to the composition is low, under high humidity, strong light and low temperature storage condition, all have good stability.

The invention relates to the technical field of beneficiation of high-calcium low-grade magnesite, in particular to a flotation decalcification agent for high-calcium magnesite and a using method of the flotation decalcification agent. Aiming at the problems that magnesite and calcareous minerals are easy to inhibit synchronously during flotation and a traditional reagent is large in dosage and high in cost, the invention provides a novel flotation reagent which can inhibit the floatability of the calcareous minerals. The flotation reagent comprises an inhibitor, a collecting agent and a foaming agent, the inhibitor is methylglycine diacetic acid (MGDA) or trisodium methylglycine diacetate (MGDA-3Na), the collecting agent is sodium oleate, and the foaming agent is 2 # oil; 30 mg-300 mg of an inhibitor, 30 mg-180 mg of a collecting agent and 2 mg-7 mg of a foaming agent are correspondingly added into every 1 L of magnesite pulp; the low-calcium magnesite concentrate obtained by flotation comprises the following main components in percentage by mass: 46.0-48.5% of MgO, less than or equal to 0.4% of SiO2 and less than or equal to 0.8% of CaO; the recovery rate of the magnesite concentrate is 65%-90% by weight, and the recovery rate of MgO in the magnesite concentrate is 60%-80% by weight.

The invention discloses a chitosanase mutant which is derived from bacillus subtilis and has the capacity of hydrolyzing chitosan to produce chitosan disaccharide per unit and belongs to a GH46 family, and application of the chitosanase mutant in hydrolyzing chitosan to produce chitosan oligosaccharide. Compared with wild type chitosanase capable of producing chitodisaccharide and chitotriose, the chitosanase mutant has the advantage that the chitodisaccharide can be produced per unit when the chitodisaccharide is hydrolyzed by the chitosanase mutant. The invention provides eight kinds of chitosanase mutants, and the mutants are obtained by carrying out site-specific mutagenesis on 21st-site glycine on the basis of wild type chitosanase and respectively mutating the 21st-site glycine into lysine, arginine, leucine, histidine, methionine, tyrosine, proline and glutamine. The mutant can hydrolyze chitosan under mild conditions to produce chitosan oligosaccharide with single polymerization degree, and can greatly relieve the difficulty in separation and purification in chitosan oligosaccharide production.