Physicochemical and kinetic characteristics of isoforms of isocitrate lyase from corn.
Three electrophoretically homogeneous isocitrate lyase (ICL) isoforms were obtained by 4-step purification from corn scutellum (ICL(1) and ICL(2)) and green leaves (ICL). Their physicochemical, kinetic, and regulatory properties were analyzed. The molecular masses of ICL(1), ICL(2) , and ICL isoforms determined by gel filtration are 164, 207, and 208 kDa, respectively. The proteins have homotetrameric quaternary structure with subunit molecular masses of 43, 48, and 47 kDa for ICL(1), ICL(2), and ICL, respectively. We found some differences in pH optimum, K(m), and regulation by divalent metal cations between ICL(1) and ICL(2) and significant similarity of ICL(2) and ICL. Based on these data, we suggest the participation of these isoforms in metabolic regulation of the glyoxylate cycle, organic acid metabolism during photorespiration in leaves and acidosis in corn seeds.
Eprintsev
A T
AT
Voronezh State University, Voronezh, 394006, Russia.
Maslova
E V
EV
Fedorin
D N
DN
Popov
V N
VN
D006038:Glyoxylates / Q000378:metabolism; D007522:Isocitrate Lyase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D003313:Zea mays / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics
D006038:Glyoxylates; D010940:Plant Proteins; D020033:Protein Isoforms; D007522:Isocitrate Lyase