Fig. 1

Conventional procedure results in inefficient thylakoid and protein extraction from P. oceanica leaves. A Thylakoids were extracted from P. oceanica leaves harvested at a 2 m depth using the conventional protocol, without PEG and VitC. (1) Sample of the filtered ground leaf mixture. (2) Final pellet after resuspending the storage buffer. (3) Centrifuged pellet of the extracted thylakoids solubilized in 2% α-DDM per mg/mL of chlorophyll (20mg DDM for 1mg chlorophyll). (4) The protein content of the solubilizate analyzed by BN-PAGE. B Coomassie-blue-stained SDS-PAGE of total protein samples extracted from P. oceanica leaves from three different growing depths using conventional Laemmli denaturing buffer. Extraction was carried out using equal amounts of leaf material and equal volumes of protein extracts were loaded on the gels. C The concentration of soluble polyphenols in P. oceanica leaves from the three different growing depths per leaf chlorophyll. GAE gallic acid equivalent. Data are represented as the median, quartiles, and border values of 4 technical replicates. Different letters indicate significant differences at P < 0.05, as determined using the Shapiro–Wilk normality test followed by the Student’s t-distribution analysis. Data and calculations are presented in Additional file 1: Data S1