An antibody against the NDH‐K subunit of the NAD(P)H‐dehydrogenase from the cyanobacterium Synechocystis sp. PCC6803 was used to isolate a subcomplex of the enzyme from Triton X‐100 solubilized total membranes by immunoaffinity chromatography. The isolated subcomplex consisted of seven major polypeptides with molecular masses of 43, 27, 24, 21, 18, 14 and 7 kDa. The amino‐terminal amino acid sequences of the polypeptides were determined. By comparing the sequences with the amino acid sequences deduced from DNA, three proteins were identified as NDH‐H (43 kDa), NDH‐K (27 kDa) and NDH‐I (24 kDa). A fourth subunit (NDH‐J, 21 kDa) was identified by Western blot analysis with an NDH‐J antibody.

The maleylacetate reductase from Pseudomonas sp. strain B13 functioning in the modified ortho pathway was purified and digested with trypsin. The polypeptides separated by high-performance liquid chromatography were sequenced. Alignments with the polypeptides predicted from the tfdF and tcbF genes located on plasmids pJP4 of the 2,4-dichlorophenoxyacetate-degrading Alcaligenes eutrophus JMP134 and pP51 of the 1,2,4-trichlorobenzene-degrading Pseudomonas sp. strain P51 as well as polypeptides predicted from the tftE gene located on the chromosome of the 2,4,5-trichlorophenoxyacetate-degrading Burkholderia cepacia AC1100 were obtained. In addition, the deduced protein sequence encoded by the nucleotide sequence downstream of clcD on plasmid pAC27 of the 3-chlorobenzoate-degrading Pseudomonas putida AC866 was tested for homology. Significant sequence similarities with the polypeptides encoded by the tfdF, tcbF, and tftE genes as well as the nucleotide sequence downstream of the clcD gene gave evidence that these genes might encode maleylacetate reductases. A NAD-binding motif in a ␤␣␤-element was detected.

No abstract