Comparison of extraction methods and analysis of enzymatic characteristics of in-vertase from the fruit of Rosa roxburghii
Convertase(sucrase)of Rosa roxburghii fruit affects the fruit growth,development and quality formation by regulating sucrose decomposition.Different extraction methods could affect the extraction effi-ciency of plant invertase and its activity.Effect of six methods for extracting invertase from the fruit of Gui-nong No.7 R.roxburghii by two ways of sample preparation,grinding fruits in liquid nitrogen and in extrac-tion buffer on ice,were compared.The enzymatic characteristics of soluble invertase were explored.The re-sults showed that the activities of invertases were seriously destroyed by grinding fruit in liquid nitrogen,espe-cially those of cell wall-bound invertase(CWI)and neutral/alkaline invertase(N/A-INV),which were totally inactivated.When fruits were ground on ice,the activity of crude soluble invertase extracted by Hepes-NaOH method revealed to be the best.The enzyme activities of SAI,CWI and N/A-INV were the highest,which were 3.16,2.09 and 2.09 μmol(glucose,fructose)/[g(FW)·h],respectively,followed by phosphate-Na method.Regarding to specific enzymatic activity,the Hepes-NaOH method was the most appropriate.The re-sults of enzymatic characteristics showed that SAI had the highest enzymatic activity at pH value of 4.5-5.0 with suitable temperature of 60 ℃,and a Km of 87.15 mmol/L for its substrate of sucrose.N/A-INV showed the highest enzymatic activity at pH value of 8.5 with suitable temperature of 45-50 ℃,and had a Km of 3.46 mmol/L for its substrate of sucrose.The results provide a foundation for the extraction of sucrose invertase and the further study of the biological function of sucrose invertase.
Rosa roxburghii fruitinvertasesucraseextraction methodsenzymatic properties
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