Monitoring of chemical and enzymatic hydrolysis of water-soluble proteins using flow-injection analysis with fluorescence detection and an aqueous eluant containing 2-p-toluidinylnaphthalene-6-sulfonate as the fluorescent probe.
The exposed hydrophobicity of proteins, which is due to the hydrophobic regions located on their surfaces, enhances the fluorescence intensity of the probe 2-p-toluidinylnaphthalene-6-sulfonate (2,6-TNS) by the formation of a complex. During the hydrolysis of a protein, the average exposed hydrophobicity of the substrate continuously changes with incubation time, and these changes are immediately reflected by a corresponding change in the fluorescence intensity of the 2,6-TNS/substrate complex. Therefore, 2,6-TNS seems to be a good probe to monitor the course of the depolymerization processes of proteins. In this work, bovine serum albumin and alpha-casein have been hydrolyzed both chemically and enzymatically, and the course of the reactions is monitored by using flow-injection analysis (FIA) with fluorescence detection and a buffered aqueous eluant containing 2,6-TNS as the fluorescent probe. Results indicate that the time evolution of the fluorescence intensity of the 2,6-TNS/substrate complex can be correlated with the initial concentration of the parent protein, in mass per unit volume, the hydrolytic activity added, and the time evolution of the mean chain length of the substrate. In addition, because the time elapsed between injection of the sample into the FIA system and measurement of the corresponding fluorescence intensity is only a few seconds, this methodology could be a useful tool for on-line monitoring of processes for the production of protein hydrolysates.
Sentandreu
E
E
Instituto de Agroquímica y Tecnología de Alimentos (CSIC), P.O. Box 73, 46100-Burjassot, Valencia, Spain.
Carbonell
J V
JV
Sendra
J M
JM
D015374:Biosensing Techniques / Q000379:methods*; D002364:Caseins / Q000032:analysis / Q000737:chemistry*; D017022:Flow Injection Analysis / Q000379:methods*; D005470:Fluorometry / Q000379:methods; D006868:Hydrolysis; D057927:Hydrophobic and Hydrophilic Interactions; D009282:Naphthalenesulfonates / Q000737:chemistry*; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000032:analysis / Q000737:chemistry*; D013381:Subtilisins / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry
D002364:Caseins; D009282:Naphthalenesulfonates; D010446:Peptide Fragments; C114674:alpha-casein (142-149); D014867:Water; D012710:Serum Albumin, Bovine; C009497:2-(4-toluidino)-6-naphthalenesulfonic acid; D013381:Subtilisins