## 4 Protein Characterization Methods
### Spectrometry  
Fourier Transform Infrared (FTIR) spectroscopy is used to obtain information about the structural composition of proteins, especially when it comes to their secondary structural conformation [27]. Mass spectrometry (MS) can be an accurate protein identification tool and electrospray ionization (ESI) and matrix-assisted laser desorption ionizations/time  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Identified Proteins** & **Molecular Weight** & **Method** & **Ref.** \\ \hline \multirow{6}{*}{_Ascophlyllum nodosum_} & \multirow{2}{*}{Protein profile} & \multirow{2}{*}{From 2.6 to 3.8 kDa} & \multicolumn{2}{c}{HPLC and SEC (HPSEC);} \\  & & & macroporous HPLC column & \\  & & & with particle size of 4-6 μm & \\  & & & and pore size of 150–300 Å; & \\ \hline \multirow{6}{*}{_Saccharina_} & Trypanothione reductase and & \multirow{6}{*}{51, 41, 40, 39 kDa} & \multirow{6}{*}{\
\begin{tabular}{c} HPSEC and SDS-PAGE; 4–20\% \\ Precast Mini-Protein® linear \\ gel; two serially connected \\ columns—1 st with 5 μm \\ particle size, 150 Å pore size, \\ 2 nd with 5 μm particle size \\ and 300 Å pore size. \\ \end{tabular} } \\  & ATP synthase subunit beta & \multirow{2}{*}{
\begin{tabular}{c} HPSEC and SDS-PAGE; 4–20\% \\ Precast Mini-Protein® linear \\ gel; two serially connected \\ columns—1 st with 5 μm \\ particle size, 150 Å pore size, \\ 2 nd with 5 μm particle size \\ and 300 Å pore size. \\ \end{tabular} } \\  & & & and pore size. \\ \hline \hline \end{tabular}
\end{table}
Table 6: Protein isolation and characterization using chromatographic methods in different seaweed species.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Identified Proteins** & **Molecular weight** & **Method** & **Ref.** \\ \hline \multirow{6}{*}{_Eisenia bicyclis_} & EHEP (_Eisenia_ & & \\  & hydrolysis enhancing protein) & 25 kDa & SDS-PAGE and 2D-PAGE & [111] \\ \hline \multirow{6}{*}{_Furcellaria_} & \multirow{2}{*}{R-PE} & \multirow{2}{*}{\(\sim\)25 kDa} & SDS-PAGE using 4–15\% Mini-Protein® & [106] \\  & & & TGX Stain Free Precast Gel. & \\ \hline \multirow{6}{*}{_Himantalia_} & \multirow{2}{*}{5 proteins} & 71.6, 53.7, 43.3, 36.4, & Tris-Tricine-SDS-PAGE using 10–20\% & \\  & & 27.1 kDa & Mini-Protein® Tris-Tricine Precast Gel. & \\ \hline \multirow{6}{*}{_Laminaria japonica_} & LJGP (_Laminaria_ & & SDS-PAGE on 15\% gels; periodic \\  & _japonica_ novel glycoprotein) & \multirow{2}{*}{\(\sim\)10 kDa} & acid-Schiff staining for glycoprotein & \\  & One prominent area of & & bands. & \\ \hline \multirow{6}{*}{_Palmaria palmata_} & \multirow{2}{*}{\begin{tabular}{c} One prominent area of \\ staining (suspected of \\ being subunits of \\ phycoerythrin or other \\ phycoolipproteins). \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} \multirow{2}{*}{\(\sim\)20 kDa} \\ -20 kDa \\ -20 kDa \\ -20 kDa \\ -20 kDa. \\ \end{tabular} } & SDS-PAGE using a Mini-Protein® II & \multirow{2}{*}{
\begin{tabular}{c} \\ \(\sim\)20 kDa \\ -21.5 g/100 \\ ml. acrylamide resolving gel. \\ \end{tabular} } \\  & 2 proteins: PYP1 and & PYP1: 10 kDa, \\ \multirow{2}{*}{_Pyropia yezoensis_} & PYP2 (_Pyropia yezoensis_ & SDS-resistant dimer; \\  & porphyrin 1 and 2). & PYP2: 10 kDa. & SDS-PAGE using a 18\% acrylamide gel. \\ \hline \hline \end{tabular}
\end{table}
Table 5: Protein isolation and characterization using SDS-PAGE methods in different seaweed species.  
of-flight (MALDI-TOF) can also be important tools [27]. Examples of their application to seaweed proteins are shown in Table 7.