Student Research Publications

A rapid micro-scale method for the extraction and analysis of protein marine samples




Nguyen, R. T.*, and H. R. Harvey


Marine Chemistry 45:1-14


A micro-scale method for the extraction and analysis of proteins in particulate material was developed by applying the bicinchoninic acid (BCA) assay together with a ribulose-1,5-diphosphate carboxylase (RuDPCase) as a new standard. The BCA assay was modified for the rapid analysis of particulate protein collected on filters, and provides several advantages over other methods currently in use. Firstly, it is not sensitive to free amino acids or chitin which may complicate other methods. Secondly, reagent and reaction products are highly stable, allowing greater precision. As the principal algal protein and a potentially important component of detritus, RuDPCase is proposed as a preferred standard for systems where photo-synthetically-derived carbon is the principal input. The protein amino acid composition of the diatom Thalassiosira fluviatilis, the prymnesiophyte Isochrysis galbana, the cyanobacterium Synechococcus sp., suspended particulate and sediment trap material showed good agreement with the RuDPCase standard, supporting its use in algal protein assays. In a comparison of the BCA and modified Lowry assays, RuDPCase consistently exhibited a lower absorbance response than bovine serum albumin (BSA), suggesting that present field estimates of protein to date are conservative. The combination of the modified BCA assay and more appropriate protein standard should allow for more quantitative estimates of protein content in marine samples.


Rodger Harvey, Ph.D.


Khiem Nguyen, University of Maryland, College Park
The REU students are indicated with an asterisk (*).

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