MONITORING AND OPTIMIZATION OF FRACTIONAL PROTEIN PRECIPITATION BY FLOW-INJECTION ANALYSIS

A rapid at-line analysis system has been established for monitoring an d optimising fractional protein precipitation. The system consists of a continuous precipitation device, a miniature centrifugal separator a nd a flow-injection analyser, all under control of a supervisory micro computer. The flow-injection analyser is used to assay alcohol dehydro genase (ADH) activity and total protein concentration subsequent to am monium sulphate precipitation from clarified baker's yeast homogenate. The relative flow-rates of the precipitant and the clarified cell hom ogenate are adjusted to cover the complete solubility profile. Corresp onding enzyme and protein solubilities are measured and the use of the at-line microcentrifuge and flow-injection analyser is shown to give good agreement with solubility profiles derived by off-line measuremen t. A method for defining the optimum fractionation conditions from the measured solubility profiles is demonstrated. Additionally, a prelimi nary study of the control of the fractional precipitation process is p resented using an empirical equation to fit the solubility profiles an d using this as a model to maintain a required setpoint by feedback co ntrol.