th  - 1988 - 51st ENC Conference

192 RESOLUTION ENHANCEMENT OF PHOSPHORUS-31 SPECTRA
I
THE USE OF CDTA IN PERCHLORIC ACID EXTRACTS OF DICTYOSTELIUM DISCOIDEUM
Kenneth L. Williamson* and Ethel F. Fromm*
Department of Chemistry, Mount Holyoke College, South Hadley, MA 01075
Dramatic increases in resolution of 31p spectra have been found in
perchloric acid extracts of the cellular slime mold, Dictyostelium discoideum,
by using CDTA (trans-l,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid
hydrate) in place of the traditional EDTA (ethylenediaminetetraacetic acid) to
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complex with cations. These high resolution spectra have been used to study
the phosphorus metabolism of D, discoideum during all stages of its
development during the 24 hr time period in which it undergoes, under
conditions of starvation, development from single-celled amoebae to a
multicellular organism containing stalk cells and spores. The present study
has focused on the latter part of the developmental process.
IADDITIVITY OF CARBON-13 SPIN-LATTICE RELAXATION TIMES IN OCTENES
Kenneth L. Williamson*, Maureen A. Simonds* and Thomas R. Stengle
*Department of Chemistry, Mount Holyoke College, South Hadley, MA 01075
Department of Chemistry, University of Massachusetts, Amherst, MA 01003.
Carbon-13 spin lattice relaxation times have been measured for a number of
isomeric octenes in order to explore the relationships between T I and
molecular dynamics and conformations. Systematic trends were observed in the
relaxation times so that an empirical relationship could be derived which
allows one to estimate the T I of a given carbon atom by summing additivity
parameters based on the location of the given carbon relative to the double
bond, to methyl groups, and to centers of branching. These additivity
parameters were obtained by performing a linear multiple regression analysis
on the Tl'S of individual carbons in the octenes. The T I of a given carbon
atom can then be derived by simply summing appropriate combinations of
regression coefficients in exactly the same way that 13C chemical shifts can
be calculated.
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