SECONDARY STRUCTURE OF BETA-HYDROXYDECANOYL THIOL ESTER DEHYDRASE, A 39-KDA PROTEIN, DERIVED FROM H-ALPHA, C-ALPHA, C-BETA AND CO SIGNAL ASSIGNMENTS AND THE CHEMICAL-SHIFT INDEX - COMPARISON WITH THE CRYSTAL-STRUCTURE

Nearly complete backbone H-1, N-15 and C-13 Signal assignments are rep orted for beta-hydroxydecanoyl thiol ester dehydrase, a 39-kDa homodim er containing 342 amino acids. Although N-15 relaxation data show that the protein has a rotational correlation time of 18 ns, assignments w ere derived from triple-resonance experiments recorded at 500 MHz and pH 6.8, without deuteration. The Chemical Shift Index, CSI, identified two long helices and numerous beta-strands in dehydrase. The CSI pred ictions are in close agreement with the secondary structure identified in the recently derived crystal structure, particularly when one take s account of the numerous bulges in the beta-strands. The assignment o f dehydrase and a large deuterated protein [Yamazaki et al. (1994) J. Am. Chem. Sec, 116, 11655-11666] suggest that assignment of 40-60 kDa proteins is feasible. Hence, further progress in understanding the che mical shift/structure relationship could open the way to determine the structures of such large proteins.