Studies of limited proteolysis on purified ferredoxin-NADP+ reductase with various proteases were performed in the presence and absence of the flavoprotein ligands. Both the diaphorase and the ferredoxin-dependent activities of the enzyme were followed as well as the proteolytic pattern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with further characterization of the polypeptides produced. These experiments revealed that only two regions of the flavoprotein are susceptible to the attack of the proteases used: (a) the N-terminal chain which can be cleaved only up to Lys35 and (b) the sequence segment 235-250. It can be inferred that these regions are on the surface of the protein molecule and presumably have a very flexible conformation adaptable to the protease active site. The deletion of the N-terminal region up to Thr36 of the native reductase (Mr 35,000) produced a truncated form (Mr about 31,000) which had full diaphorase activity but lost the capacity to catalyze the ferredoxin-dependent reaction. Proteolytic cleavage at the 235-250 segment of the sequence yielded a nicked protein (Mr about 30,000 by gel filtration; 23,000 plus 7,000 in denaturing electrophoresis) devoid of both activities. Protection by the flavoprotein ligands implies that the 23-35 region of the sequence is part of the binding site for ferredoxin and the 235-250 polypeptide segment is in the NADP(+)-binding site.
Structure-function relationship in spinach ferredoxin-NADP+ reductase as studied by limited proteolysis / G. Gadda, A. Aliverti, S. Ronchi, G. Zanetti. - In: THE JOURNAL OF BIOLOGICAL CHEMISTRY. - ISSN 0021-9258. - 265:20(1990 Jul 15), pp. 11955-11959.
|Titolo:||Structure-function relationship in spinach ferredoxin-NADP+ reductase as studied by limited proteolysis|
ALIVERTI, ALESSANDRO (Secondo)
RONCHI, SEVERINO (Penultimo)
ZANETTI, GIULIANA (Ultimo)
|Parole Chiave:||protein ; flavoprotein ; enzyme ; photosynthesis ; protein-protein inteaction ; protein-substrate recognition ; catalytic mechanism ; protein modification|
|Settore Scientifico Disciplinare:||Settore BIO/10 - Biochimica|
Settore BIO/11 - Biologia Molecolare
|Data di pubblicazione:||15-lug-1990|
|Appare nelle tipologie:||01 - Articolo su periodico|