38results about How to "Reduce racemization" patented technology

The present invention provides an improved process for preparing β-D and β-L 2′-C-methyl-nucleosides and 2′-C-methyl-3′-O-ester nucleosides.

The present invention provides methods, apparatus and kits for synthesizing assembled peptides and proteins on a solid phase with sequential ligation of three or more unprotected peptide segments using chemoselective and mild ligation chemistries in aqueous solution. Also provided are methods of monitoring solid phase sequential ligation reactions using MALDI or electrospray ionization mass spectrometry of reaction products.

The invention provides a solid phase method of secretin, which comprises the following steps: 1) selecting an appropriate solid phase carrier; 2) coupling amino acids one by one according to a solid phase synthetic method; 3) splitting for obtaining a crude peptide; 4) obtaining the secretin by purifying the crude peptide, wherein, the solid phase synthesis employs Fmoc-strategy, and false proline is used for replacing parts of serine in the peptide chain during the solid phase synthesis. The solid phase method of secretin provided by the invention has the advantages of simple operation, small impurity, easy purifying and high yield, and is beneficial to realization of industrialization.

The solid-phase synthesis method of octreotide acetate of the present invention belongs to the field of polypeptide synthesis. First, the acetalization product is bonded to a polymer resin; the bonded product is sequentially bonded to the protected amino acid residues and deprotected to obtain an octapeptide resin; the octapeptide is cut from the resin to make an aqueous solution, and Octreotide is made after natural oxidation in the air; glacial acetic acid is added to the octreotide aqueous solution and then freeze-dried to make octreotide acetate. The invention has simple synthesis process, easy operation, shortened process time, small reaction ratio, saved raw materials, reduced cost, improved yield and purity, fewer side reactions and by-products, convenient purification, and beneficial to mass production.

The invention relates to a method for separating L-glutamic acid and L-pyroglutamic acid from a glutamic acid refinement mother solution. The method comprises the following steps: 1) carrying out vacuum concentration on the glutamic acid refinement mother solution, cooling to crystallize, and centrifugating, wherein the solid is the L-glutamic acid crude product, and the liquid is for later use; 2) washing the L-glutamic acid crude product with water to obtain pure L-glutamic acid; and 3) heating the liquid obtained in the step 1), carrying out pressurized pyrogenic reaction, cooling, concentrating, cooling to crystallize, centrifugating, collecting the precipitate, adding water to a saturated state, recrystallizing, cooling, and carrying out centrifugal separation to obtain the L-pyroglutamic acid. The method is simple in technical process, and can well solve the problem of the separation technique for glutamic acid and pyroglutamic acid, thereby achieving the goals of enhancing the L-glutamic acid refinement yield and coproducing the L-pyroglutamic acid.

Disclosed herein is a method for preparing a hyaluronan-drug conjugate. The method uses the ethyl cyano(hydroxyimino)acetate / diisopropylcarbodiimide coupling system in a homogeneous reaction phase, which unexpectedly improves the substitution rate and substitution efficiency of hyaluronan-drug conjugates for various drugs.