Abstract
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 (K(m) = 0.7 μM) 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.
Original language | English (US) |
---|---|
Pages (from-to) | 4305-4310 |
Number of pages | 6 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 93 |
Issue number | 9 |
DOIs | |
State | Published - Apr 30 1996 |
Keywords
- phosphotransferase
- pyrophosphate
ASJC Scopus subject areas
- General