SMALL-MOLECULE ANALOGS OF PHOSPHOLIPID METAL-ION BINDING-SITES - POTENTIOMETRIC AND SPECTROSCOPIC STUDIES OF MG(II) AND CA(II) COMPLEXES OFCYCLOHEXANE-1,2,4-TRIOL TRISPHOSPHATES
Jc. Amburgey et al., SMALL-MOLECULE ANALOGS OF PHOSPHOLIPID METAL-ION BINDING-SITES - POTENTIOMETRIC AND SPECTROSCOPIC STUDIES OF MG(II) AND CA(II) COMPLEXES OFCYCLOHEXANE-1,2,4-TRIOL TRISPHOSPHATES, Bioorganic chemistry, 22(2), 1994, pp. 198-215
Studies on the Mg(II) and Ca(II) complexes of four diastereomeric cycl
ohexane-1,2,4-triol trisphosphates were conducted using H-1 NMR, P-31
NMR, and calcium ion selective electrode (ISE) titrations. Based on th
e trends in Mg(II) and Ca(II) ion affinity, the 2,4-phosphate groups w
ere concluded to be the primary determinants of the metal ion binding
behavior of the 1,2,4-trisphosphates. Results from the proton and meta
l ion binding studies of the 1,2,4-trisphosphates indicate that the 1,
2,4-trisphosphates satisfy two of the criteria as analogs of phospholi
pid-metal ion binding sites: (1) anionic groups which interact in meta
l ion binding, and (2) metal ion affinity constants determined by both
ISE and P-31 NMR titrations are comparable to the metal ion affinity
observed for phosphatidylserine vesicles. In particular, the all-cis t
risphosphate diastereomer, (+/-)-(1R, 2S, 4S)-cyclohexane-1,2,4-triol
trisphosphate, is the only 1,2,4-trisphosphate to exhibit a higher aff
inity for Ca(II) ion than Mg(II) ion. A higher Ca(II) ion affinity tha
n Mg(II) ion affinity is characteristic of the behavior observed for p
hosphatidylserine vesicles or monolayers. (C) 1994 Academic Press, Inc
.