The Preparation Of L-ribose By Biological Enzyme Method

L-Ribose is an important medicine intermediate, having significantmedicinal value. All kinds of L-Ribose derivatives are widely applied inanti-tumor and anti-virus field. L-Ribose belongs to extremely raremonosaccharide nonexistent naturally, being synthesised or convertedfrom other matters. The preparation method has carried out the transitionto new biotransformation method recently from early chemical synthesisways. Seeking more activitical isomerase from different strain sources isthe trend of L-Ribose preparation abroad now. The research of rare sugaris relatively less, but the demand of L-Ribose is huge. So we need tostrengthen basic exploration about L-Ribose preparation which is onepoint of rare sugar research at the present time.The preparation of L-Ribose places emphasis up on fundamentalresearch in the study. The strains L.F (B.S) after domestication andscreening from our lab can produce L-AI (MPI). Fermentation conditions and culture medium of the tow strains are respectively optimized. Toobtain L-AI and MPI crude enzyme solution, L.F and B.S fermentationliquid are extracted by ultrasonic crushing method. Then the crudeenzymes are purified preliminarily. The enzymatic characteristics of L-AIand MPI are studied after determination condition of enzyme activity.Finally, L-AI and MPI are applied in the course of preparation ofL-Ribose, meanwhile the effect factors on conversion reaction areinvestigated.The results of study show that L.F (B.S) can produce L-AI (MPI).The suitable fermentation conditions are respectively as below, culturetemperature of L.F or B.S is37℃or30℃, initial pH is7.5or7.2,inoculation amount are both3%. The total protein content of L.F and B.Sfermentation liquor are0.052mg/mL (4U/mL) and0.068mg/mL(4.5U/mL). The terms of ultrasonic crushing include action time (10min)and power (0.2kW). The components (from30%⁶0%or40%⁷0%) arecollected through ammonium sulfate precipitation, standing for L-AI orMPI. The results of enzymatic characteristics show that the optimaltemperature and pH of reaction are50℃,7.5(L-AI) or40℃,7.2(MPI);The metal ions Mn²⁺and Co2+both increase enzyme activity of L-AI andMPI.0.5mM Mn²⁺(for L-AI) and0.5mM Co2+(for MPI) respectivelyexhibit the most significant effect. While the Cu2+and Hg2+both restrainenzyme activity of L-AI and MPI. LFAI (BS-MPI) shows the highest substrate specificity to L-Arabinose (L-ribulose); the enzyme half-life t1/2of L-AI (MPI) are176min (40℃) and196min (30℃). In the process ofpreparation of L-Ribose, L-AI and MPI are added together for Commontransformation with adjusting the reaction conditions, after6hours, thetotal conversion rate can arrive at22.75%.