Isolation,Purification, Some Properties And Modification Of Groups Of Acid Phosphatase From Spring Onions

Acid phosphatase, referred to as ACP, is a kind of sulfhydryl enzyme which catalyzes monoester phosphate hydrolysis and releases inorganic phosphorus in acidic conditions.In plants, acid phosphatase directly involves in the metabolism transport process of the phosphorus,good to form a good plant root structure,plays an important role in adapting to low phosphorus stress. In the Clinical,the change of ACP level in serum is an important indicator of the disease in diagnosis of prostate cancer,cervical cancer,stomach cancer,spinal cord injury. In the environmental pollution monitoring,the changes of ACP level is also an indicator.In recent years acid phosphatase caused wide attention of scholars both at home and abroad. So far,there are a variety of sources of acid phosphatase get a detailed researchbut there is not any research reports about Spring Onions acid phosphatase Therefore,this article takes the source of Spring Onions of cheap and wide range as experimental material,purifying the acid phosphatase and study some properties about it,so as to provides more data to study and apply the acid phosphatase.The results were as follows:1. Separation and purification of ACP from Spring OnionsThe Acid phosphatase which showed a single band on SDS-PAGE had been purified from Spring Onions by homogenization,ammonium sulfate precipitation,CM-Sepharose chromatography and Superdex-200chromatography8%of Acid phosphatase activity was recovered and its multiple of purification was234.1,its specific activity was527.4U/mg.2. Properties of ACP from Spring OnionsThe relative molecular mass of the subunit was about57.8KD The enzyme had a relative molecular mass of59.6KD.so the Spring Onions Acid phosphatase may has the same of two subunits.The pH and optimum temperature of this enzyme were5.4and50℃respectively. The Spring Onions Acid phosphatase is sensitive to heat.The Km of Spring Onions Acid phosphatase towards pNPP was3.63mmol/L.3. Influence of different organic solvent,chemical reagent and metal ions on the activity of ACP from Spring OnionsMethanol,ethanol,isopropanol have a stronger inhibitory effect on the enzyme,10%of glycerol has an activation function,ascorbic acid,hydrogen peroxide are also the inhibition,ascorbic acid is a bigger inhibition, and EDTA and urea show some of activation the action on the enzyme.Ca2+、Ag+、Zn2+、Cu2+、 Co2+、Pb2+show certain inhibition to Spring Onions acid phosphatase,Cu2+shows very obvious inhibitory effect,and finally makes the enzyme almost completely inactivation, the K+, Mg2+has not obvious effect on the enzyme,low concentration of Mn show larger inhibition than high concentration.4. Chemical modification of ACP from Spring OnionsThe modification results showed that:the mercapto group of cysteine,the indolyl group of tryptophane disulfide bond and serine should be function groups of ACP from Spring Onions,but disulfid bonds,Imidazole of His,sulfide group of Met,Arg,and Lys residues should not be function groups of it.