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Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.45 [2008] >
IJBB Vol.45(5) [October 2008] >
| Title: | Plastocyanin microheterogeneity in Scenedesmus acutus MT8 |
| Authors: | Dimitrov, Mitko I
Donchev, Anthony A
Toromanov, Georgi R
Getov, Vladimir I
Toncheva-Panova, Tonka G |
| Keywords: | Plastocyanin
Microheterogeneity
Dimorphism
Isoelectric focusing
Chromatofocusing |
| Issue Date: | Oct-2008 |
| Publisher: | CSIR |
| Abstract: | Two total plastocyanin (PC) fractions — loosely bound (lPC) and strongly bound (sPC) were extracted (84% and 16%,
respectively) from the homogenate of Scenedesmus acutus MT8. Two-fold isolation-purification procedure including DE-52
chromatography separated lPC into a smaller oxidized [lPC (II)] and a larger reduced [lPC(I)] fractions, in contrast to sPC,
where sPC(II) greatly dominated over sPC(I). Analytical isoelectric focusing (IEF) separated lPC(II) into two main fractions
only in the presence of 8 M urea, implying microheterogeneity. Preparative IEF in immobiline pH-gradient of 3.2-4.1
separated lPC(II) into two blue fractions – a more alkaline lPC'(II) and a more acidic lPC''(II), which were probably
stereoisomers. Their UV-Vis spectra exhibited rarely observed tryptophane (291.5 nm) and some differences at 270 and 287
nm. The exact molecular masses of apo-/holo-lPC (10131 Da/10194 Da) were determined by mass spectrometry. The
number of -SH groups was determined from the mass difference between alkylated with 4-vinylpyridine (4-VP) and nonalkylated
protein. Additionally, a simple procedure for simultaneous separation of both primary structure and stereoisomers
of PC was developed. |
| Page(s): | 310-316 |
| ISSN: | 0301-1208 |
| Source: | IJBB Vol.45(5) [October 2008]
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