BOOKS dues. Heteronuclear 15 N- 13 C spin-spin coupling across the peptide bond, for example, provides one means for ob taining sequence-related assignments in proteins; isotopic labeling with 13 C- 15 N is a prerequisite for this. The method has been used to make such assignments in proteins as large as 23 kDa and is the most promising ap proach for large biomolecules. Wuthrich and his group have ex ploited an alternative means of achiev ing sequential assignments, which, al though limited to smaller proteins, does not require isotopic substitution. Wuthrich's method takes advantage of the nuclear Overhauser effect (NOE) or cross relaxation between pairs of Ή spins that are within about 5 Â of one another. For example, cross peaks in the two-dimensional NOE spectrum of a protein in H2O solution are expected between certain pairs of protons in neighboring residues, depending on the nature of the amino acids and their relative conformation. Assignment of a high fraction of the proton resonances in a molecule makes it possible to use additional NOE peaks to describe the secondary and tertiary structure of the protein or nucleic acid.
DET
The success of the NMR approach in determining solution structures may be gauged by the fact that more than 40 protein structures currently are being analyzed or refined by this method. It is reassuring that NMR-derived solution structures have been similar to those determined by single-crystal diffraction methods. NMR provides an advantage when a protein cannot be crystallized, but not when a protein has low solubility. Several well-documented cases demonstrate the power of NMR to assay structural homogeneity and check the validity of sequencing data. Wuthrich's book presupposes that the reader has some prior knowledge of NMR spectroscopy, yet provides relatively easy access to its applications to proteins and nucleic acids. Students will find it helpful, and those active in the field will appreciate it as a useful reference.
Books Received Quantitative Electron-Probe Microanalysis. V. D. Scott, G. Love, Eds. 1 + 345 pp. John Wiley & Sons, 605 Third Ave., New York, N.Y. 10016.1987. $32.95
for
GC
DET
Laboratory Robotics: A Guide to Planning, Programming, and Applications. W. Jeffrey Hurst, James W. Mortimer, xi + 129 pp. VCH Publishers, 220 E. 23rd St., New York, N.Y. 10010.1987. $24.95 Binding Constants: The Measurement of Molecular Complex Stability. Kenneth A. Connors, xiv + 411 pp. John Wiley & Sons, 605 Third Ave., New York, N.Y. 10016. $69.95 Chromatographic Theory and Basic Principles. Jan Jonsson, Ed. xi + 396 pp. Marcel Dekker, 270 Madison Ave., New York, N.Y. 10016. 1987. $79.75 Nuclear Environmental Chemical Analysis. Juraj Tolgyessy, Edwin H. Klehr. 185 pp. Ellis Horwood Limited, Market Cross House, Cooper St., Chichester, West Sussex, P 0 1 9 1EB, England. 1987. $64.95 Phosphorus-31 NMR Spectroscopy in Stereochemical Analysis. John G. Verkade, Louis D. Quin. xvi + 717 pp. VCH Publishers, 220 E. 23rd St., Suite 909, New York, N.Y. 10010. 1987. $125.00
GC
for
NITRO-COMPOUNDS
TANDEM TID
high s p e c i f i c i t y , 1.0 pg s e n s i t i v i t y
^^lmu^t_aj^e_ou_s _thermionic signals
_E_X£LJJ §J[VE _T H_ER M\ PJiljÇ_K^N_l_^A U P J Î
Drug Compounds
Nitro Additive in Diesel Fuel TID-2-H
p ( D complex sample many unresolved components In detector at same time
2
/AIR
NP mode responds to most N-compounds
TID-1-N2 re
8ponS
nly
t0
TID-1-N_ ®° 1 2 nitro-addltive requires minimal chromatographic separation
response to electronegative compound structures
many other signal combinations are possible
simple to operate - no special gas flow or purity requirements - easy change to other response modes - ceramic ionizing elements DETector Engineering & Technology, inc.
DETector Engineering & Technology, inc.
2212 Brampton Rd, Walnut Creek, CA 9 4 5 9 8
2212 Brampton Rd. Walnut Creek. CA 9 4 5 9 8
4 1 5 / 9 3 7 - 4 2 0 3 , TX 4 2 5 9 0 0 SWIFT ATT XET
4 1 5 / 9 3 7 - 4 2 0 3 , TX 4 2 5 9 0 0 SWIFT ATT XET
CIRCLE 32 ON READER SERVICE CARD ANALYTICAL CHEMISTRY, VOL. 60, NO. 1, JANUARY 1, 1988 · 33 A
