Analysis of needle proteins and N-terminal amino acid sequences of two photosystem II proteins of western white pine (Pinus monticola D. Don)

A method is described for extracting needle proteins from mature western white pine (Pinus monticola D. Don) trees. Extracted proteins were separated into 26 components by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The predominant protein component (32-39%) had a molecular weight of 57 kDa. The second most predominant protein component (14-25%) had a molecular weight of 16 kDa. The amino acid composition of the twenty-six protein components was determined and a few selected proteins were subjected to further amino acid sequence analysis. Of these, two proteins, designated as Pin m I and Pin m II, were identified by sequence homology with other Photosystem II proteins. The Pin m I and Pin m II proteins had molecular weights of 22.6 kDa and 23.4 kDa, respectively. Pin m I had a much higher proline content than Pin m II.