Sequential Assignment and Solution Secondary Structure of Doubly Labelled
Ribonuclease Sa

Crystal structure is of RNAse SA at
ph 6.7 in the presence of 22% ammonium
sulfate and 0.1 m phosphate buffer, at
room temperature.
NMR assignments are at ph 5.5, no buffer
at 303 K

Sequential assignment and solution secondary structure of doubly labelled ribonuclease Sa.

Laurents, DV, Perez-Ca?adillas, JM, Santoro, J, Rico, M.
Schell, D, Hebert, EJ, Pace, CN & Bruix, M.
"Sequential Assignment and Solution
Secondary Strucuture of Doubly Labbelled
Ribonuclease Sa" for submission to J.
Biomol. NMR (1998)

A considerable degree of variability exists in the way that 1H, 13C and 15N
chemical shifts are reported and referenced for biomolecules. In this article
we explore some of the reasons for this situation and propose guidelines for
future chemical shift referencing and for conversion from many common 1H, 13C
and 15N chemical shift standards, now used in biomolecular NMR, to those
proposed here.

Wishart, D. S., Bigam, C. G., Yao, J., Abildgaard, F., Dyson, H. J.,
Oldfield, E., Markley, J. L., and Sykes, B. D.
J. Biomol. NMR 6, 135-140 (1995).

1H, 13C and 15N chemical shift referencing in biomolecular NMR.

The 2D COSY, TOCSY and NOESY spectrum
were recorded in H2O/D2O and in D2O

These are the conditions used for
samples 1, 3 AND 4, where the solvent
was H2O/D2O (90%/10%) by volume.
The pH* was adjusted without buffer
using small amounts of HCl or NaOH.
There were no salts.

These are the conditions used for
sample 2, where the solvent
was D2O.
The pH* was adjusted without buffer
using small amounts of HCl or NaOH.
There were no salts.

Used for assigning the spectra. Automatic peak picking in 2D