Abstract
The complete amino acid sequence of the alpha chain of histidine decarboxylase of Lactobacillus 30a has been established by isolation and analysis of the eight methionine-containing tryptic peptides of this chain. These peptides provide the overlaps required to order all nine peptides derived by complete cyanogen bromide cleavage of the alpha chain (Huynh, Q.K., Vaaler, G.L., Recsei, P.A., and Snell, E.E. (1984) J. Biol. Chem. 259, 2826-2832). Ordering of six of the latter peptides was confirmed by isolation and analysis of four peptides derived by incomplete cyanogen bromide cleavage. The alpha chain is composed of 226 residues and has a molecular weight of 24,892 calculated from the sequence. These results and the previously determined sequence of the beta chain (Vaaler, G.L., Recsei, P.A., Fox, J.L., and Snell, E.E. (1982) J. Biol. Chem. 257, 12770-12774) establish the complete amino acid sequence of the enzyme and of the pi chain of prohistidine decarboxylase. The latter is composed of 307 amino acids and has a calculated molecular weight of 33,731. Four segments of the pi chain sequence are repeated. The bond between Ser-81 and Ser-82 that is cleaved during proenzyme activation is in an uncharged portion of the sequence that is rich in serine and threonine residues and is predicted to be part of a beta sheet structure.
Highlights
The complete amino acid sequence of the Q chain of 0 subunits, definesthe complete sequenceof prohistidine histidine decarboxylaseof Lactobacillus 30a has been decarboxylase
In the preceding paper [5] we reported the determination of the amino acid sequences of the nine peptides derived by complete cleavage of the a chain with cyanogen bromide
In thispaper we describe the ordering of these peptides by isolation and analysis of the methionine-containing tryptic peptides
Summary
In the preceding paper [5] we reported the determination of the amino acid sequences of the nine peptides derived by complete cleavage of the a chain with cyanogen bromide. Overlaps between the tryptic peptides and each of quence These results and the previously determined the cyanogen bromide peptides were composed of at least two sequence of the j3 chain 12770-12774) establish the complete amino acid sequence of the enzyme and of the T chain of prohistidine decarboxylase. In thepreceding paper [5] we described the isolation and acid sequence from positions 157-197 contains 14 hydrophosequence analysis of peptides derivedfrom the cy chain by bic and only two chargedresidues, and the sequencefrom cyanogen bromide cleavage. This segment of the chain contains 17 charged amino acids, many of which are clustered
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