The amino acid sequence of chicken muscle enolase
Of the 433 residues in chicken muscle enolase, 421 have been positively identified by liquid-phase sequencing and placed in the sequence. The sequence is therefore 97% complete. Only about 21% of the sequence was determined by sequencing large peptides generated from IOBA or CNBr cleavage procedures. The remaining 79% was established from smaller peptides produced by clostripain or staph, protease digests of whole enolase, H(A) and H(B). The sequence of the smaller hydroxylamine fragment H(B) is complete and represents 153 residues at the N-terminus of the enolase molecule. The sequence of the larger c-terminal hydroxylamine fragment H(A), is 96% complete i.e. 268 out of 280 residues have been positively identified and-placed in the sequence. An essential carboxyl group has been demonstrated to exist by chemical modification of the enzyme with carbodii-mide and glycine methyl ester. However, the location of this carboxyl group in the sequence was not established. The postulated active site residues, histidine-191 and arginine-414, which were tentatively placed in the yeast enolase sequence by Chin et al., (1981b), are conserved in the chicken enolase sequence. Secondary structure predictions were carried out and indicate a lack of extensive a-helical- and (3 sheet- preferring regions, where only 1% of the sequence was estimated to exist in beta-pleated sheet structure and 12% in a-helical structure. The predictive method was by McLachlan (1978) and was done on the Bristol Computer with the assistance of Dr H Muirhead.