th  - 1988 - 51st ENC Conference

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HIGH RESOLUTION IOC-IH SHIFT CORRELATION WITH FULL [H-IH DECOUPLING.
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M. PERPICK-DUMONT, *a W.F. REYNOLDS a AND R.G. ENRIQUEZ, b DEPARTY~NT OF
CHEMISTRY UNIVERSITY OF TORONTO AND INSTITUTO DE QUIMICA, Utah7 ...... zDAD
AUTONOM~ DE M~XICO.
A COLOC-like sequence combined with a selective BIRD refocussinz
pulse is used to generate fully IH-IH decoupled 13C-IH shift correlated
spectra with F 1 line widths of ca. 7Hz. The sequence is generally freer
of artifacts and more sensitive than earlier sequences measured under
comparable conditio:=s. A minor modification of the sequence, which
allows simultaneous observation of IJcH couplings, is particularly
useful for determination of small differences in IJcH for non-equivalent
CH 2 groups. IH chemical shifts and IJcH couplings can be measured with
a precision of < iHz, except in cases of strongly coupled CH 2 groups.
However, even in these cases, it may still be possible to de:ermine
very small chemical shift differences by simolation-of ~' ~
_LI~ non--first
order behavior.
laC AND *SN MASS SPECTRA OF LABELED
STAPHYLOCOCCAL NUCLEASE CRYSTALS
Holly B.R. Cole* and Dennis A. Torchia
NIDR, National Institutes of Health, Bethesda, HD 20892
Osing genetically transformed E. Coli (provided by
Professor John Gerlt), we have labeled staphylococcal.
nuclease (Nase), an 18 kDa enzyme , with a variety of
selectively enriched amino acids. We report MASS spectra of
Nase, labeled with [methyl-lee] methionine and [15N] valise.
Lyophilized Nase has relatively broad, poorly resolved lines
indicating local disorder. In contrast, crystalline Nase has
well resolved lines whose chemical shifts may be compared to
Nase chemical shifts observed in solution. This technique
provides the means to compare protein structures in the
crystalline and solution states using the same experimental
parameters. In addition, because of the high sensitivity and
resolution of the MASS spectra, one has the opportunity to
study protein internal dynamics at numerous assigned single
atomic sites in the protein crystals.
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