Carbon-13 relaxation studies on the manganese(II)-adenosine 5'-triphosphate complex in solution

Abstract

have characterized the four PHP isomers treated in this work by synthetic organic methods. Their results are in agreement with those presented herein, and upon comparing the requisite labor involved the advantages of using cmr spectroscopic techniques as compared with traditional chemical methods are readily apparent.

A ternary acetylcholine—manganese—ATP complex

“…From the proton-manganese distances obtained in this study it is difficult to suggest a definite geometry for the ternary complex. Inspection of molecular models reveals that these distances are consistent with a model in which the manganese ion is associated with the a-and/~-phosphates and the N-7 nitrogen of ATP [10,11 ], the positively charged N-trimethyl group of acetylcholine with the 7-phosphate, the acetyl group being hydrogen-bonded either to the ribose hydroxyls or to the adenine NH2 group. It is emphasized that while such models make chemical sense they do not stem directly from the present results.…”

The Kinetics and Mechanisms of Exchange in the Binary System Manganese(II) – Adenosine 5′-Triphosphate

“…The inconsistencies in the interpretation of the previous metal ion -ATP kinetic study by n.m.r. (39) have been pointed out in previous papers (17,35,40,41).…”

“…exchange rate T,-'. It has previously been shown (17) The analysis of the ATP concentration dependence on T2,-' is shown in Table 1. Since the ligand-to-metal ion ratio is very large, the free ATP concentration is essentially equal to the total ATP concentration in solution.…”

“…exchange rates are related by the following The ligand sites are defined as free ligand, L(aq), outer sphere ligand, M(aq)L, and inner sphere ligand, ML, and are referred to a s species a, b, and c respectively. The three site exchange theory that has previously been developed (16,17) can now be applied to this system. The change in the transverse relaxation caused by the paramagnetic metal ion in the consecutive three site exchange mechanism is where kb = T2b-1 + kba + kbc The outer sphere complex is usually in the fast exchange region while the inner sphere comkc = Tzc-l + kcb plex may be in either the fast or slow (chemical T2j is the usual transverse relaxation time in the j controlled) region in the n.m.r.…”

“…The overall stability constant is In addition to the above Eigen-Tamm mech-'pecies of present in L(aq), anism, another common exchange mechanism M(aq)L, and ML as a, b, and c, may also be present. This mechanism is the the three-site exchange theory previously pre-direct ligand exchange and is written sented (16,17) may be applied to the present system. In the Appendix it is shown that the (16).…”