One possibility is that, although peptide sequences determine the first level of substrate specificity [30], structural determinants essential for optimal substrate recognition are missing in the sequences used here.
Furthermore, only 34 of the 278 substrates of strain Philadelphia are missing in strain Paris, 30 in strain Lorraine or 25 in strain HL 0604 1035 (Additional file 1, Table S1).
There are reactions for which the preprocessing could not determine if they were really unbalanced (e.g. if chemical structures are missing for their substrates), but they are still not included in the model.
Data concerning the effects of these treatments on cardiac substrate utilization, energetics or aldose reductase activity are missing.
Interestingly, periplasmic substrate-binding proteins, which usually are an integral part of such transport systems, are missing in most ABC-type carriers.
In Geobacillus sp. JF8, both xynB1 and xynA2 orthologs are missing, implying that this strain is incapable of utilizing the xylotriose substrate.
However, comprehensive approaches are missing.
The proposed active site contains certain conserved features of a sialidase: a nucleophilic tyrosine with its associated glutamic acid, and two of the usual three arginines that interact with the carboxylic acid group of the substrate, but is missing the first arginine and the aspartic acid that acts as an acid/base in all sialidases studied to date.
This pattern suggests that a critical biosynthetic step or substrate may be missing or limited, and under strong environmental influence.
However, a simple methodology to compare different gas supply strategies using gaseous substrates from different sources is missing.
