The complete amino-acid sequence of D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the extreme thermophilic eubacterium Thermotoga maritima has been determined by classical automated sequence analysis of peptides derived by chemical fragmentation with cyanogen bromide and enzymatic cleavages with specific proteases. 2. The protein contains 332 amino acids per subunit. Its sequence is as follows: (sequence; see text) 3. Comparing the given sequence with those of the enzymes from the moderate and extreme thermophilic bacteria Bacillus stearothermophilus and Thermus aquaticus, 63% and 59% identity are observed. Alignment of the sequences of GAPDHs from a variety of sources yields one deletion (one amino acid) and one insertion (two amino acids). 4. Thermal stability is caused by minute adjustments of the local three-dimensional structure. Previous 'strategies of thermal adaptation' in terms of preferred amino-acid exchanges are not in accordance with the present sequence data.
