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Expression of the lipA gene regulates lipase production in Acinetobacter calcoaceticus at the genetic level. This was gleaned from an investigation of the involvement of a fatty acyl-responsive DNA-binding protein in the regulation of expression of the A. calcoaceticus lipBA operon. It was also found that the level of active extracellular LipA may be influenced at the level of proteolytic stability or instability of the lipase.

The chemistry of the p-coumaric acid chromophore of the photoactive yellow protein (PYP) from the purple sulfur bacterium Ectothiorhodospira halopila was studied. Findings indicated that p-coumaric acid is connected to Cys 69 by thiol ester, the thiol ester bond reacts to dithiothreitol, performic acid and high pH in the same way it reacts to disulfide bridges, and spectral characteristics of the PYP chromophore is affected by the protein structure, the thiol ester bond and the ionization of the phenolic proton.

Phenotypic analysis of five Acinetobacter calcoaceticus mutants lacking extracellular lipase, which were generated via insertion mutagenesis, revealed four lipolytic enzymes. Biochemical tests classified four mutants as export mutants, while the additional mutant, designated AAC302, exhibited showed mutation 0.84 kbp upstream of lipA, although it displayed the LipA- phenotype. DNA sequencing of the region revealed an open reading frame that encodes a protein required for the production of extracellular lipase. It is suggested that this protein acts as a lipase-specific chaperone.