Robert A. Mitchell, Ph.D.

Phosphoryl chloride is an inexpensive phosphorylating agent widely used for the laboratory and commercial production of compounds of biological interest, such as mononucleotides and stable derivatives of ascorbic acid. The compositions and properties of partial hydrolysis mixtures as well as the identities of phosphorylating agents are unknown. ¹⁸O GC electron impact mass spectrometric analysis and ³¹P NMR analysis were used to measure the compositions of partial hydrolysis mixtures and to demonstrate that the compositions are kinetically rather than thermodynamically determined. Mass spectrometric analysis of 18O distributions in phosphate esters derived from partial hydrolysis mixtures pointed to the existence of precursor intermediates with phosphorus in an expanded coordination state. A rate equation based on asymmetric bisite catalytic activation was derived and used successfully to fit published kinetic and exchange data obtained from both F₁ and F₀F₁ mitochondrial ATPase, as the system changes from unisite to multisite catalysis.

R.A. Mitchell. Kinetics of hydrolysis of PCl₅ in situ as evaluated from the partial hydrolysis products formed in [¹⁸O] water. J. Chem. Soc., Dalton Trans. 1069-1073, 1997.

R.A. Mitchell and T. L. Stemmler. Composition and Properties of Partial Hydrolysis Mixtures of Phosphoryl Chloride as Determined by ¹⁸O Mass Spectrometry and ³¹P NMR: Implications for Their Use as Phosphorylating Agents for the Synthesis of Phosphate Esters. XIX International Congress of Biochemistry and Molecular Biology, July 20-24, 2003, Toronto, Canada,.Abstract.

R.A. Mitchell. A speculative approach for analyzing the ATP-driven transition from a unisite to a bisite ATP hydrolytic mechanism in F₀F₁. Biophysical Society, 48th Annual Meeting, Feb. 14-18, 2004, Baltimore, USA, (Abstract in press).