Study On The Characteristic And Application Of Penicillin Acylase

The effect of organic solvent, temperature and pH value on the activity of the industrial widely used penicillin G acylase(PGA) were studied in this thesis. The reaction conditions, including the reaction medium, temperature, pH value and the concentration of substrate, were optimized and used in the synthesis of amoxicillion with PGA as the catalytist. The following works have been done:1. Some organic solvents were selected according to the law of logP for the further investigation about their effect on the activity of PGA. The preferable organic solvent which has slightly effect on the activity of PGA was chosen out by monitoring the change of the activity of PGA. Glycerin, ethylene glycol and dimethyl sulphoxide(DMSO) showed slightly effect on the activity of PGA. The effects of temperature and pH value on the activity and stability of PGA were also investigated. It was found that the activity of PGA increased and the stability of PGA decreased as the temperature increased from 20℃to 55℃. The most suitable temperature was 40℃. The activity of PGA increased firstly and then decreased when the pH changed from 6 to 8. However, the stability of PGA decreased as the pH value increasing. The activity and stability of PGA reached to the best point at pH 6.5 or 7.2. The Methyl p-hydroxyphenylglycinate (p-OH-PGME) was synthesized from the p-hydroxyphenylglycinate dane salt. The IR and melting point analysis were used to characterized the synthesized p-OH-PGME. The apparent solubility of p-OH-PGME in some solvents was measured. The n-butyl alcohol and ethylene glycol are better solvents for p-OH-PGME. The better solubility of substrate is propitious to the synthesis ofβ-lactam antibiotic.3. The reaction conditions in the synthesis of amoxicillion using PGA as catalyst were optimized. The conversion ratio of 6-APA and hydrolytic ratio of p-OH-PGME are investigated under different conditions. As a result, the favorable reaction conditions including the reaction medium, temperature, pH value of solution, concentration of 6-APA , the ratio of 6-APA and p-OH-PGME are ethylene glycol-buffer solution, 20℃, 6.5, 75 mmol/L, 1:2, respectively.