Purified inositol hexakisphosphate kinase is an ATP synthase: diphosphoinositol pentakisphosphate as a high-energy phosphate donor.
Diphosphoinositol pentakisphosphate (PP-IP5) and bis(diphospho)inositol tetrakisphosphate (bis-PP-IP4) are recently identified inositol phosphates that possess pyrophosphate bonds. We have purified an inositol hexakisphosphate (IP6) kinase from rat brain supernatants. The pure protein, a monomer of 54 kDa, displays high affinity (Km = 0.7 microM) and selectivity for inositol hexakisphosphate as substrate. It can be dissociated from bis(diphospho)inositol tetrakisphosphate synthetic activity. The purified enzyme transfers a phosphate from PP-IP5 to ADP to form ATP. This ATP synthase activity indicates the high phosphate group transfer potential of PP-IP5 and may represent a physiological role for PP-IP5.
Voglmaier
S M
SM
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Bembenek
M E
ME
Kaplin
A I
AI
Dormán
G
G
Olszewski
J D
JD
Prestwich
G D
GD
Snyder
S H
SH
D000818:Animals; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007295:Inositol Phosphates / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000302:isolation & purification* / Q000378:metabolism*; D016548:Prosencephalon / Q000201:enzymology*; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D007295:Inositol Phosphates; C079849:1-diphosphoinositol pentakisphosphate; D017856:Phosphotransferases (Phosphate Group Acceptor); C099438:inositol hexakisphosphate kinase; D006180:Proton-Translocating ATPases