Voglmaier S M, Bembenek M E, Kaplin A I, Dormán G, Olszewski J D, Prestwich G D, Snyder S H
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Proc Natl Acad Sci U S A. 1996 Apr 30;93(9):4305-10. doi: 10.1073/pnas.93.9.4305.
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.
二磷酸肌醇五磷酸（PP-IP5）和双（二磷酸）肌醇四磷酸（双-PP-IP4）是最近发现的含有焦磷酸键的肌醇磷酸。我们从大鼠脑上清液中纯化了一种肌醇六磷酸（IP6）激酶。这种纯蛋白是一种54 kDa的单体，对肌醇六磷酸作为底物表现出高亲和力（Km = 0.7 microM）和选择性。它可以与双（二磷酸）肌醇四磷酸合成活性分离。纯化后的酶将一个磷酸基团从PP-IP5转移到ADP上以形成ATP。这种ATP合酶活性表明PP-IP5具有高磷酸基团转移潜力，可能代表了PP-IP5的一种生理作用。
