Shelf life and stability have been recurring problems in attempts to use enzymes and lipids in industry. Thermostable enzymes and liposomes are desired in order to further their usage in commercial applications. More stable enzymes are needed for applications in chemical synthesis and in biosensors, for example. Liposome stability is important for drug delivery applications, and the U.S. Food and Drug Administration requires stringent quality control measures. New quick and reliable methods for measuring biophysical properties of these lipid vesicles will be needed as per the published FDA guidelines if their use is to be expanded in the medical industry.

Gene locus AF0227 of the hyperthermophilic archaeon, Archaeoglobus fulgidus, is predicted to encode a thermostable fusion protein, AroQ, comprising chorismate mutase, prephenate dehydratase, and prephenate dehydrogenase activities. This work describes the first characterization of a trifunctional AroQ. In this study, the A. fulgidus aroQ gene was cloned and overexpressed in Escherichia coli, and the three activities were confirmed with LC/MS and UV-Vis spectroscopy. The fusion of these proteins may work in this organism to protect and efficiently convert the temperature labile substrate, prephenate.

The core membrane lipid of archaea has a unique isoprenoid ether lipid structure, typically consisting of a sn-2,3-diphytanylglycerol diether or sn-2,3-dibiphytanyldiglycerol tetraether core modified with a variety of polar headgroups. APCI-MS and TLC studies confirmed that the tetraether/diether lipid ratio increases with higher organism growth temperatures, and up to 2 pentacycles on the tetraether lipid chains of A. fulgidus core membrane lipid are added at higher temperature. Further, ESI-MS and TLC analysis suggested the presence of inositol, glycosyl, and ethanolamine headgroups on the diether and tetraether lipid.

Multi angle laser light scattering was used to monitor the swelling of egg lecithin vesicles and estimate the thermal area expansivity as 2.6 ± 1.0 × 10^-3°C^-1. These measurements agree well with literature values and were further confirmed with dynamic light scattering measurements. In addition, the thermal area expansivity of diphytanyl ether lipid vesicles was estimated to be 3.2 ± 0.05 × 10^-3°C^-1. This higher TAE value may be due to the greater disorder introduced by the bulky methyl groups of the isoprenoid chains at higher temperatures.