Function of C-terminal peptides on enzymatic and interfacial adsorption properties of lipase from Gibberella zeae

A New Phospholipase D from Moritella sp. JT01: Biochemical Characterization, Crystallization and Application in the Synthesis of Phosphatidic Acid

A new phospholipase D from marine Moritella sp. JT01 (MsPLD) was recombinantly expressed and biochemically characterized. The optimal reaction temperature and pH of MsPLD were determined to be 35 °C and 8.0. MsPLD was stable at a temperature lower than 35 °C, and the t_1/2 at 4 °C was 41 days. The crystal structure of apo-MsPLD was resolved and the functions of a unique extra loop segment on the enzyme activity were characterized. The results indicated that a direct deletion or fastening of the extra loop segment by introducing disulfide bonds both resulted in a complete loss of its activity. The results of the maximum insertion pressure indicated that the deletion of the extra loop segment significantly decreased MsPLD’s interfacial binding properties to phospholipid monolayers. Finally, MsPLD was applied to the synthesis of phosphatidic acid by using a biphasic reaction system. Under optimal reaction conditions, the conversion rate of phosphatidic acid reached 86%. The present research provides a foundation for revealing the structural–functional relationship of this enzyme.

Exploring the influence of phospholipid monolayer conformation and environmental conditions on the interfacial binding of Gibberella Zeae lipase

The involvement of different parameters on Gibberella zeae lipase (GZEL) membrane binding were characterized by using monomolecular film technology and circular dichroism spectroscopy. Among four kinds of phospholipid monolayers, 1,2‑dimyristoyl‑sn‑glycero‑3‑phosphoethanolamine have the highest maximum insertion pressure (MIP) value. Comparing the GZEL adsorption to phosphatidylcholine monolayers with different acyl chains in sn-1 and sn-2 positions, the higher MIP values were found for 1,2‑dilauroyl‑sn‑glycero‑3‑phosphocholine. Significantly improvement between 1,2‑dioleoyl‑sn‑glycero‑3‑phosphocholine and 1,2‑distearoyl‑sn‑glycero‑3‑phosphocholine suggested that the presence of fatty acid unsaturation may affect protein adsorption by changing the chemical structure in each phospholipid. The MIP value was shown higher (48.6 mN m^-1) at pH 5 and pH 6 (47.5 ± 1.9 mN m^-1) but decreased significantly (34.2 mN m^-1) at pH 9. This may indicate that the proportion of helices in the protein decreases with the alteration of the catalytic center, thus affecting the binding of the protein to its substrate. The MIP values obviously decreased with increasing salt ion concentration, suggesting that excessive salt ion concentration may destabilize the secondary and tertiary structures of the protein, thereby affecting the characteristics of its adsorption at the interfaces. Present studies improve our understanding on the protein-membrane interaction of this enzyme.