NMR chemical shifts from structure -"summary"

 Netters,
   There have not been many responses concerning calculation of chemical shifts
 from structure.  Below are the (edited) comments I received.  Many of the
 studies referred to are still in press -- so perhaps interest in this area
 is picking up.
 From: FRAENKEL -x- at -x- MPS.OHIO-STATE.EDU  Gideon Fraenkel, Chem. Dept., Ohio
 State
      There are two programs which can be used to calculate NMR chemical
 shifts starting with ab initio wavefunctions. They are based on much the
 same theory (Ramsay equation) and work in similar fashion. One is ARMPAC
 which comes from Jim Bowman, Northern Illinois, the other IGLO from
 Kutzelnig, Ruhr Universitaet. You probably need a 6-31G* calculation,
 fully optimized. For recent references I suggest you look at a current
 volume of Specialist Periodical Reports on NMR, Royal Society of Chemistry.
 Ditchfield at Dartmouth is someone who works in this field. Bill Kern and I
 wrote some papers in the seventies on ab initio calculations of chemical
 shifts.
      If by dynamic NMR you mean the effects of exchange and conformational
 interconversion on NMR spectra I refer you to the book by myself and J. I.
 Kaplan, NMR of Chemically Exchanging Systems, Academic Press, 1980, or
 the book edited by Jackman and Cotton,Dynamic NMR Spectroscopy, Academic Press,
 1975. Gerhard Binsch wrote software, DNMR1 to DNMR6(?) which are distributed by
 QCPE,Indiana University. These only handle first order processes. We have
 all purpose software that let you calculate any exchanging system you want
 to imagine. However YOU have to derive the density matrix equations.
      Turning to proteins there are many contributions to chemical shifts
 which IGLO and ARMPAC do not take into account. These include electrostatic
 interactions and solvation.
 >From PCJ -x- at -x- PSUVM.PSU.EDU   Peter Jurs, Chemistry Dept., Penn State
 We have been working in this area for several years.
 We work exclusively with small molecules. An overview
 of our approach is given in Analytical Chemistry, 61, 1115A
 (1989). We have published a number of papers in Analy. Chem.
 and Analy. Chim. Acta. We are now in the process of merging
 the database retrieval method and model building methods for
 prediction of CNMR of small molecules.
 >From case -x- at -x- scripps.edu    David Case, Scripps Institute
 There is a great deal of current interest in looking at regularities in
 chemical shift distributions on protons and carbon-13 in proteins.  In the
 realm of "semi-empirical" to "empirical" calculations, Klara
 Osapay and I
 have a paper in press in JACS that surveys proton chemical shifts in 21
 proteins whose crystal structures are known.  We find that with a combination
 of ring currents, peptide group anisotropy calculations, and electrostatic
 effects, that a reasonably good account of shifts of protons bonded to carbons
 can be obtained; root-mean-square deviations for about 5700 shifts are about
 0.2 ppm for all shifts, and somewhat less, about 0.13 ppm, for methyl groups.
 The formulas used involve fitting parameters, but the best values match
 what is known, or thought to be known, about expected strengths of the various
 contributions.  Our electrostatic model is very crude, and I know others are
 working on more complex models.
 As far as I know, out study is the first study of protein shifts at this
 level of empiricism since the early 80's, when complete assignments were first
 becoming available for proteins.  Of course, there is a much literature on
 ring currents and magnetic anisotropy contributions to proton chemical shifts
 in organic systems....
 My reading of the prevailing opinion amongst NMR people about similar
 calculations for nucleic acids is that that problem is much more difficult.
 For one thing, we don't know the detailed structure of oligonucleotides in
 solution (and crystal structures may be less relevant than for proteins);
 for another, ring current contributions from many rings are likely to be
 involved, which may make things difficult to untangle.  It is sometimes possible
 to intepret particular (unusual) shifts in structural terms, but I have not
 seen a convincing general account.
 	A preliminary account of some of our shift work appeared in
 Biochemical Pharmacology 40: 15-22 (1990).  In terms of surveys,
 look for a paper soon to appear in J Mol Biol on proton
 shifts in proteins, and to the recent note in JACS by the NIH group on
 regularities in 13-C shifts in proteins.
 Q2) Is software currently available for STRUCTURE -> NMR chemical shifts
 The software we used to generate the data for our upcoming JACS paper
 (computing proton chemical shifts from protein structures using
 empirical formulas) is available via anonymous ftp from riscsm.scripps.edu.
 Look for the file pub/shifts.tar.Z
 >From kmoore -x- at -x- ncsc.org  Kevin Moore, NCS
       My group at Duke University has been doing ab initio calculations
 for some time under the direction of Don Chesnut, and we have very good
 results with Carbon and Nitrogen (<5% error) and not so good with others (it
 is a mixed bag). Hydrogen shifts are good, but the range is small, and we
 have done a limited amount of large scale testing. Some recent reviews
 of the status of ab initio work in this area can be found in:
 (1)D.B. Chesnut, Ann. Rep. NMR Spect., 21, 51 (1989).
 (2)W. Kutzelnigg and M. Schindler, NMR Basic Principles and Progress,
    Springer-Verlag, Berlin, Vol. 23, 1990.
 >From Ken Butenhof, CWRU
 	Those wanting an introduction to calculation of ring current effects
 may be interested in the (old) review:
  Progress in NMR spectroscopy, Vol 13 pp 303-344 by C.W. Haigh and R.B. Mellion
 --
 					Ken Butenhof
 					Department of Pediatrics
 					Case Western Reserve University
 					Cleveland, Ohio  44106
 --
 					Ken Butenhof
 					Department of Pediatrics
 					Case Western Reserve University
 					Cleveland, Ohio  44106